Inferensys

Prompt

Multi-Turn State Contract Definition Prompt

A practical prompt playbook for agent platform teams defining explicit state schemas, update rules, and merge semantics for multi-turn tool interactions in production AI workflows.
Developer demonstrating multi-agent tool use, agent tool selection interface on laptop, casual tech demo moment.
PROMPT PLAYBOOK

When to Use This Prompt

Define the job, reader, and constraints for the Multi-Turn State Contract Definition Prompt.

This prompt is for agent platform teams who need to define an explicit, typed state contract before building a multi-turn tool-use agent. The job-to-be-done is converting an informal understanding of what the agent should remember across turns into a machine-readable schema that governs state initialization, field updates, merge semantics, and validation rules. The ideal user is an infrastructure developer or AI engineer who is integrating a stateful agent into a production system and needs the contract to be enforced programmatically, not just described in a design doc. Required context includes a list of all tools the agent can call, the data each tool produces or requires, and the expected lifecycle of a session (e.g., short-lived task vs. long-running conversation).

Do not use this prompt when the agent is stateless, when all context is passed inline by the application layer, or when you are prototyping a single-turn workflow. It is also the wrong tool if you are looking for a generic system prompt that describes agent behavior—this prompt produces a state schema, not behavioral instructions. The output is a technical artifact meant to be consumed by validation harnesses, context management middleware, and state reconciliation logic. If your team does not have the infrastructure to enforce the contract at runtime, the schema will become documentation that drifts from reality. In high-risk domains such as healthcare, finance, or safety-critical operations, the generated contract must be reviewed by a human who understands the domain's data integrity requirements before it is wired into production.

Before using this prompt, gather the tool definitions, expected session duration, and any existing state management patterns your platform already enforces. The prompt works best when you provide concrete tool schemas and example turns rather than abstract descriptions. After generating the contract, the next step is to implement the validation harness described in the Implementation Harness section, which will catch schema violations, drift, and incomplete state before they corrupt agent reasoning.

PRACTICAL GUARDRAILS

Use Case Fit

Where the Multi-Turn State Contract Definition Prompt delivers value and where it introduces risk. Use these cards to decide if this prompt fits your current agent infrastructure challenge.

01

Good Fit: Agent Platform Teams

Use when: You are building agent infrastructure that other developers will depend on. Explicit state contracts prevent downstream teams from guessing which fields persist across turns. Guardrail: Version the contract alongside your tool definitions and treat breaking changes as API breaks.

02

Bad Fit: Single-Turn Tool Calls

Avoid when: Your agent makes one tool call and returns a result with no follow-up turns. State contracts add unnecessary schema overhead for stateless interactions. Guardrail: Use a lightweight function-calling prompt instead and only introduce state contracts when multi-turn coordination is required.

03

Required Input: Tool Dependency Graph

What to watch: Without a clear map of which tool outputs feed into which downstream calls, the contract will miss critical dependencies. Guardrail: Document the tool dependency graph before generating the state contract. Validate that every required upstream field exists before a dependent call proceeds.

04

Required Input: Merge Semantics

What to watch: Ambiguous merge rules cause silent state corruption when multiple tool calls update the same field. Guardrail: Define explicit merge strategies (replace, append, merge-by-key, conflict-error) for every field that can be written by more than one tool.

05

Operational Risk: Stale State Propagation

What to watch: Cached tool results from early turns can corrupt reasoning in later turns if the underlying data has changed. Guardrail: Annotate every state field with a TTL or freshness indicator. Pair this prompt with a stale context detection prompt that flags expired data before it enters reasoning.

06

Operational Risk: Context Collision in Parallel Calls

What to watch: Concurrent tool calls that write to overlapping state fields can produce non-deterministic results. Guardrail: Namespace state by tool call ID or enforce sequential execution for tools that share write targets. Validate state consistency after parallel tool execution completes.

PROMPT PLAYBOOK

Copy-Ready Prompt Template

A reusable prompt template that defines a typed state contract with update rules and merge semantics for each turn of a multi-turn tool-use agent.

This prompt template produces a typed state contract for an agent that calls tools across multiple turns. It forces explicit decisions about which fields are required, which are optional, how each field is updated per turn, and what happens when tool results conflict. Use this template before building the agent's execution loop—it becomes the source of truth that your state manager, validators, and evals all reference. The output is a machine-readable schema plus human-readable rules, not a generic description of state.

text
You are defining a typed state contract for a multi-turn agent that uses external tools. The agent maintains state across tool calls, and each turn may read or update that state. Your job is to produce a complete, unambiguous contract that a state manager can enforce.

## INPUTS
- Agent purpose: [AGENT_PURPOSE]
- Available tools and their schemas: [TOOL_SCHEMAS]
- Maximum turns per session: [MAX_TURNS]
- Risk level: [RISK_LEVEL]  // one of: low, medium, high, critical
- Regulatory context (if any): [REGULATORY_CONTEXT]

## OUTPUT SCHEMA
Return a JSON object with the following structure:
{
  "contract_version": "string",
  "state_schema": {
    "required_fields": [
      {
        "name": "string",
        "type": "string",
        "description": "string",
        "source": "string",  // which tool or input populates this field initially
        "update_rule": "replace | append | merge | conditional",
        "merge_strategy": "string | null",  // required if update_rule is merge
        "validation": "string",  // regex, range, enum, or custom rule
        "nullable": false
      }
    ],
    "optional_fields": [ /* same structure as required_fields */ ]
  },
  "turn_rules": [
    {
      "turn_number": 1,
      "allowed_tools": ["string"],
      "required_state_before": ["string"],
      "state_updates": [
        {
          "field": "string",
          "action": "set | append | merge | delete",
          "condition": "string | null"
        }
      ],
      "conflict_resolution": "string"
    }
  ],
  "conflict_rules": {
    "same_turn_conflict": "string",
    "cross_turn_staleness": "string",
    "tool_result_divergence": "string"
  },
  "drift_detection": {
    "checks": ["string"],
    "remediation": "string"
  },
  "human_approval_gates": [
    {
      "trigger": "string",
      "fields_under_review": ["string"],
      "approval_action": "string"
    }
  ]
}

## CONSTRAINTS
- Every field in state_schema must have an explicit update_rule. Do not use "implicit" or "context-dependent" as a rule.
- Turn rules must cover every turn from 1 to [MAX_TURNS]. If later turns are open-ended, define the pattern that repeats.
- Conflict rules must handle: two tools writing the same field in one turn, a tool returning data that contradicts prior state, and state that has not been refreshed for more than [STALENESS_THRESHOLD] turns.
- If [RISK_LEVEL] is high or critical, every state mutation must have a corresponding human_approval_gate entry.
- Drift detection checks must be executable by a validator, not subjective. Use field-level comparisons, schema checks, and timestamp-based staleness.
- Do not invent tools. Use only the tools provided in [TOOL_SCHEMAS].
- If [REGULATORY_CONTEXT] is provided, add an "audit_fields" array to state_schema containing every field that must appear in audit logs.

## EXAMPLES
[EXAMPLES]

## OUTPUT
Return only the JSON object. No markdown fences, no commentary.

Adaptation notes: Replace every square-bracket placeholder before use. [TOOL_SCHEMAS] should contain the actual JSON schemas of your tools, not just names—the model needs argument types and return shapes to define update rules correctly. [EXAMPLES] is critical: provide at least two worked examples showing a complete contract for a simpler agent so the model learns the expected level of detail. If you omit examples, the output will be vague about merge strategies and conflict resolution. For high-risk domains, add a post-generation step that runs the contract through a schema validator and a human reviewer before it touches production state.

IMPLEMENTATION TABLE

Prompt Variables

Required inputs for the Multi-Turn State Contract Definition Prompt. Each placeholder must be populated before the prompt is assembled and sent. Missing or malformed variables will cause schema generation failures or silent contract drift in production.

PlaceholderPurposeExampleValidation Notes

[TOOL_REGISTRY]

List of all tools available to the agent with their input/output schemas

search_knowledge_base: {query: string, filters: object} -> {results: array, total: int}

Validate each tool entry has a name, input schema, and output schema. Reject if any tool is missing a schema definition.

[TURN_SEQUENCE]

Ordered list of tool interaction turns with expected dependencies

turn_1: search_knowledge_base, turn_2: filter_results (depends on turn_1.results)

Check that every dependency references a valid prior turn. Reject circular dependencies or references to non-existent turns.

[STATE_SCHEMA_TEMPLATE]

Target schema shape for the state contract with field types and constraints

{session_id: string, current_turn: int, tool_results: map, pending_actions: array}

Validate against JSON Schema draft. Reject schemas with ambiguous types or missing required field markers.

[MERGE_STRATEGY]

Rules for how new tool results combine with existing state

shallow_merge for tool_results, replace for current_turn, append for pending_actions

Confirm merge strategy is specified for every top-level state field. Reject if any field lacks an explicit merge rule.

[UPDATE_RULES]

Conditions under which state fields can be modified and by which turns

tool_results can only be written by the turn that produced them; pending_actions can be appended by any turn

Validate that write permissions are defined per field per turn. Reject rules that allow cross-turn overwrites without explicit approval.

[DRIFT_DETECTION_THRESHOLD]

Confidence level below which state consistency checks trigger a revalidation

0.85

Must be a float between 0.0 and 1.0. Reject values outside this range. Null allowed if drift detection is disabled.

[SESSION_LIFECYCLE]

Boundaries for state initialization, active use, and teardown

init_on_first_tool_call, active_until_timeout_300s, teardown_on_session_close

Check that init, active, and teardown phases are all defined. Reject if any lifecycle phase is missing or has an invalid duration.

[OUTPUT_SCHEMA]

Expected structure of the generated state contract document

{contract_version: string, fields: array, merge_rules: object, validation_checks: array}

Validate output schema is a valid JSON Schema. Reject if required fields like contract_version or fields are absent.

PROMPT PLAYBOOK

Implementation Harness Notes

How to wire the state contract definition prompt into an agent platform's tool execution loop with validation, drift detection, and safe defaults.

The Multi-Turn State Contract Definition Prompt is designed to be called before any tool execution begins in a new agent session or when a new tool is registered dynamically. It should run as a synchronous pre-flight step inside the agent's orchestration layer, not as a one-off design exercise. The prompt expects a description of the agent's purpose, the available tools and their schemas, and the expected multi-turn interaction pattern. Its output is a typed state contract—a JSON Schema object plus merge rules—that the agent runtime can use to initialize, validate, and update state across turns. Wire this prompt into your agent framework's session initialization hook or tool registration handler so that every session starts with an explicit, machine-readable contract rather than an implicit, drift-prone state model.

After the prompt returns the contract, the harness must perform three validation steps before accepting it. First, validate the output against a JSON Schema that requires stateSchema (a valid JSON Schema object), requiredFields, optionalFields, updateRules (a map from field name to replace, merge, append, or conditional), and driftDetection (a list of invariants to check each turn). Reject and retry if the schema is malformed or missing required keys. Second, cross-check that every field referenced in updateRules and driftDetection exists in stateSchema.properties. Third, run a deterministic merge simulation: apply a synthetic sequence of tool results against the update rules and verify no field ends up in an undefined state. Log the contract version, the model that generated it, and the validation result. For high-stakes agent deployments (finance, healthcare, infrastructure control), require a human reviewer to approve the contract before it goes live, and store the approved contract as an immutable artifact in your agent's configuration store.

At runtime, the agent executor should load the approved contract and use it to initialize an empty state object with requiredFields set to null or explicit defaults. After each tool call, the harness must apply the tool's output to the state object using the updateRules map—do not rely on the model to remember state correctly across turns. Before each subsequent tool call, run the driftDetection invariants against the current state; if any invariant fails, pause the agent, log the violation, and either request a state repair from the model or escalate to a human operator. Avoid wiring this prompt as a one-shot generator with no runtime enforcement. The contract is only as valuable as the harness that enforces it. For model choice, prefer a model with strong schema-following behavior (GPT-4o, Claude 3.5 Sonnet, or equivalent) and set temperature=0 to maximize contract stability. If your platform supports multiple models, generate the contract with the strongest available model and enforce it with a lighter model at runtime.

IMPLEMENTATION TABLE

Expected Output Contract

Fields, types, and validation rules for the typed state contract produced by the Multi-Turn State Contract Definition Prompt. Use this contract to validate agent state before and after each tool interaction turn.

Field or ElementType or FormatRequiredValidation Rule

state_schema_version

string (semver)

Must match ^\d+\.\d+\.\d+$. Reject if absent or unparseable.

session_id

string (UUID v4)

Must match UUID v4 regex. Reject if null, empty, or wrong format.

turn_index

integer >= 0

Must be non-negative integer. Reject if negative, float, or missing. Compare to previous turn_index; reject if not incremented by exactly 1.

required_fields

array of field definition objects

Each object must have name (string), type (string from allowed type enum), and description (string). Reject if array is empty or any object is missing a required key.

optional_fields

array of field definition objects

If present, same schema as required_fields. Null allowed. Reject if present but not an array.

update_rules

object

Must contain on_create (string enum: append, replace, merge, reject), on_update (string enum), and conflict_resolution (string enum: last_write_wins, merge, reject, human_approval). Reject if any key missing or value not in enum.

merge_semantics

object

Must contain strategy (string enum: shallow, deep, replace) and array_behavior (string enum: append, replace, deduplicate_by_key). Reject if strategy is deep but no max_depth (integer) provided.

drift_detection

object

Must contain checksum_algorithm (string, default: sha256), expected_checksum (string or null), and stale_after_seconds (integer or null). Reject if checksum_algorithm is not a recognized hash name.

PRACTICAL GUARDRAILS

Common Failure Modes

Multi-turn state contracts fail silently when schemas drift, merge rules are implicit, or required fields go missing. These are the most common production failure modes and how to prevent them before they corrupt agent reasoning.

01

Silent Field Dropping Across Turns

What to watch: The model omits a required field from the state update on turn N+1, causing downstream tool calls to receive incomplete context. This happens most often with optional fields that become conditionally required. Guardrail: Add a schema validation step after every state mutation that checks field presence against the contract. Reject partial updates that fail completeness checks and request the missing fields explicitly.

02

Merge Conflict on Concurrent Tool Results

What to watch: Two parallel tool calls return results that update the same state key with conflicting values. The model picks one arbitrarily or concatenates them, producing a corrupted state object. Guardrail: Define explicit merge semantics per field in the contract—last-write-wins, append-only, or conflict-flag. When a conflict is detected, pause execution and request human resolution before proceeding.

03

Stale State Reuse After Tool Failure

What to watch: A tool call fails mid-execution, but the agent continues using the pre-call state as if the operation succeeded. This produces hallucinated outcomes and incorrect downstream decisions. Guardrail: Require the agent to mark state as 'pending' before a tool call and only transition to 'confirmed' after a success response. On failure, revert to the last confirmed state and log the rollback event.

04

Schema Drift Between Contract and Runtime

What to watch: The state contract schema evolves—a field is renamed, a type changes, or a new required field is added—but the prompt still references the old schema. The model generates state objects that fail downstream validation. Guardrail: Version the state contract schema explicitly in the prompt header. Include a schema hash or version number in every state object. Validate the version match at the start of each turn and reject mismatches with a clear migration instruction.

05

Context Collision Across Session Boundaries

What to watch: State from a previous session leaks into a new session because the agent reuses cached context without resetting. This causes cross-contamination between unrelated workflows or users. Guardrail: Include a session initialization step that explicitly clears all mutable state fields before the first tool call. Use a session-scoped namespace prefix on all state keys and validate that no keys from prior sessions persist after initialization.

06

Unbounded State Growth Over Long Sessions

What to watch: The agent accumulates tool results, intermediate reasoning, and metadata across dozens of turns without eviction. The state object grows beyond the context window, causing truncation that removes critical early context. Guardrail: Define a maximum state size in the contract and a priority-based eviction policy. Mark each state field with a retention priority. When the budget is exceeded, evict low-priority fields and log what was removed so downstream turns can detect missing context.

IMPLEMENTATION TABLE

Evaluation Rubric

Criteria for testing the quality and correctness of a generated Multi-Turn State Contract Definition before integrating it into an agent harness. Use these checks in an automated eval pipeline or manual review gate.

CriterionPass StandardFailure SignalTest Method

Schema Completeness

All required fields from the input specification are present in the output contract, and no placeholder tokens remain unresolved.

Output is missing a mandatory field like [SESSION_ID] or contains a raw placeholder such as [REQUIRED_FIELD].

Parse the output as JSON and diff the top-level keys against the input specification's required fields list. Assert no values contain square brackets.

Type Accuracy

Every field in the contract uses a valid, specific type (e.g., string, integer, boolean, array, object) and matches the intended data type for that field.

A field defined as an integer in the spec is typed as a string in the contract, or a custom type is used without definition.

Validate the output against a JSON Schema generated from the input specification. Assert no type mismatches.

Merge Semantics Definition

For every field that can be updated across turns, the contract defines an explicit merge strategy (e.g., overwrite, append, merge-by-key, keep-first).

A field like [TOOL_RESULTS] lacks a merge strategy, or the strategy is ambiguous (e.g., 'update').

Extract all fields with a defined update rule. Assert that the set matches the list of mutable fields from the input spec. Check for a non-empty, valid strategy string.

Drift Detection Rule Validity

The contract includes at least one drift detection rule that compares expected state against actual tool output, with a clear mismatch action.

The drift rule references a non-existent field or the mismatch action is missing or invalid (e.g., 'ignore' for a critical state field).

Parse the drift rules block. For each rule, assert the source field exists in the contract and the action is one of 'warn', 'block', 'reconcile', or 'human_approval'.

Optional Field Handling

Optional fields are explicitly marked as optional with a defined default value or null-allowed flag, and required fields are not marked optional.

A required field like [SESSION_ID] is marked as optional, or an optional field lacks a default value, causing downstream null pointer risks.

Check the 'required' boolean for each field. Assert it matches the input spec. For optional fields, assert the 'default' attribute is present and not null unless explicitly allowed.

Schema Validation Readiness

The output contract is directly translatable into a JSON Schema or Pydantic model without manual editing.

The contract contains a circular reference, an undefined $ref, or a field description that cannot be mapped to a standard schema keyword.

Attempt to compile the output into a JSON Schema using a standard library. Assert compilation succeeds with zero errors.

Context Isolation Enforcement

The contract defines clear namespacing or scoping rules to prevent state collision between concurrent or sequential tool calls.

Two different tools write to the same top-level key without a namespacing prefix, or a global state variable is overwritable by any tool.

Scan the contract for global mutable state. Assert that all shared state is namespaced by tool name or call ID, and that write access is explicitly granted per tool.

Hallucination Check

The contract does not invent fields, tools, or state variables not present in the input specification or explicitly requested by the user.

The output includes a field like [USER_CREDIT_SCORE] that was not in the input spec, or references a tool that was not provided.

Diff the final field list against the input specification. Assert zero extraneous fields. Flag any field not in the spec for manual review.

ADAPTATION OPTIONS

Adapt This Prompt

How to adapt

Start with the base prompt and a single tool. Replace the full state schema with a flat JSON object containing only the 3-5 fields your first tool needs. Remove merge semantics and drift detection sections. Use a simple instruction: "Return the updated state object with all fields present."

code
You are defining the state contract for a single tool call. The current state is [CURRENT_STATE]. After the tool [TOOL_NAME] returns [TOOL_RESULT], produce the new state as a flat JSON object. Include all fields from the current state plus any new fields from the tool result.

Watch for

  • Fields silently dropped between turns because no schema enforces completeness
  • Tool result fields overwriting state fields with different semantic meaning
  • No detection when the state shape drifts across 5+ turns
Prasad Kumkar

About the author

Prasad Kumkar

CEO & MD, Inference Systems

Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.

His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.