This prompt is designed for SRE teams and platform engineers operating AI systems where the available tool set can change between requests due to circuit breakers tripping, load shedding, or active incident response. The core job-to-be-done is intelligent, runtime tool routing: the model receives a dynamic list of disabled tools and must select a viable alternative without exposing internal operational state to the end user. The ideal user is an infrastructure or reliability engineer embedding this prompt into a model gateway, agent harness, or tool dispatch layer that already monitors endpoint health and can inject a [DISABLED_TOOLS] list at inference time.
Prompt
Dynamic Tool Disablement Prompt Under Load

When to Use This Prompt
Defines the operational scenario, required inputs, and boundaries for using a dynamic tool disablement prompt under load.
Use this prompt when your system's tool availability is fluid and you need the model to reason about constraints that are not known at deploy time. This is common in multi-tenant platforms where a specific API endpoint might be rate-limited, a database replica might be lagging, or a payment service might be in a degraded state. The prompt expects a structured list of disabled tool names and, optionally, the reason for disablement and an estimated recovery time. Do not use this prompt for static tool routing where the disabled list is fixed, known at deploy time, or can be handled entirely in application code. It is also not a replacement for a proper circuit breaker or load shedder; it is the reasoning layer that sits behind those operational controls.
Before implementing, ensure your harness can provide a live, accurate [DISABLED_TOOLS] payload and that your observability stack can log both the disabled list and the model's final tool selection for later audit. Avoid using this prompt when the disabled tool list is empty or static, as the additional reasoning overhead provides no benefit. The next section provides the copy-ready prompt template you will adapt and inject into your tool-selection step.
Use Case Fit
Where the Dynamic Tool Disablement Prompt works, where it breaks, and the operational preconditions required before deploying it under load.
Good Fit: Active Load Shedding
Use when: your infrastructure has already detected a degraded or overloaded endpoint and you need the model to route around it without exposing internal incident state to the user. Guardrail: the disabled-tool list must be injected from a live operational control plane, not hardcoded in the prompt.
Bad Fit: Static Routing
Avoid when: the set of available tools is fixed and known at deploy time. A static tool list in the system prompt is simpler, faster, and easier to test. Guardrail: only introduce dynamic disablement when the tool availability surface changes at runtime due to incidents, maintenance, or cost caps.
Required Input: Live Disabled-Tool List
What to watch: the prompt depends on an accurate, up-to-date list of disabled tool names injected at request time. Stale or incomplete lists cause the model to select a tool that will fail downstream. Guardrail: the injection layer must fetch the disabled list from a single source of truth (feature flag, circuit breaker state, or orchestrator health check) within the same request lifecycle.
Operational Risk: Silent Degradation
What to watch: when all candidate tools are disabled, the model may hallucinate a tool call, select a disabled tool anyway, or produce a confusing refusal. Guardrail: the prompt must include an explicit fallback instruction for the zero-available-tools case, and the harness must validate that the output is a user-facing degradation message, not a tool call.
Operational Risk: Information Leakage
What to watch: the model may reveal which tools are disabled, why they are disabled, or internal incident details when explaining its routing decision to the user. Guardrail: the prompt must prohibit mentioning disabled tools by name or explaining the disablement reason. User-facing messages should describe what the user can do, not what the system cannot do.
Required Input: User-Facing Fallback Message Template
What to watch: without a templated degradation message, the model will improvise language that may be inconsistent, overly technical, or misleading. Guardrail: provide a constrained message template with placeholders for the available action and estimated recovery time. Validate that the model output matches the template structure in eval.
Copy-Ready Prompt Template
A reusable prompt that forces the model to select a tool while respecting a dynamically provided list of disabled tools, with explicit fallback and user messaging.
This prompt template is designed for SRE teams and platform engineers who need to dynamically disable tools during overload conditions without exposing internal state to the end user. The template accepts a list of currently disabled tools at runtime and instructs the model to route around them, selecting the best available alternative. It also requires the model to generate a user-facing message that explains any degradation in service without revealing which specific tools are down or why.
textSYSTEM: You are a tool-selection router operating under load-shedding conditions. Your primary directive is to select the most appropriate tool to fulfill the user's request while strictly avoiding any tool present in the disabled-tool list. ## CONSTRAINTS - You MUST NOT select, suggest, or reference any tool listed in [DISABLED_TOOLS]. - If no enabled tool can satisfy the user's intent, you MUST select the fallback tool specified in [FALLBACK_TOOL]. - You MUST generate a user-facing message stored in the `user_message` field. This message should explain any change in capability or latency without mentioning specific disabled tools, internal load states, or the disablement list itself. - If a fallback is used, the `user_message` must politely set expectations for reduced functionality or increased latency. ## AVAILABLE TOOLS [TOOL_SCHEMAS] ## DISABLED TOOLS (DO NOT USE) [DISABLED_TOOLS] ## FALLBACK TOOL [FALLBACK_TOOL] ## OUTPUT FORMAT Return a valid JSON object with the following schema: { "tool_name": "string (the selected tool)", "arguments": {}, "user_message": "string (a user-facing message explaining the action taken)", "is_fallback": boolean } USER REQUEST: [USER_INPUT]
To adapt this template, replace the square-bracket placeholders at runtime. [TOOL_SCHEMAS] should be populated with the full JSON schema definitions of all available tools, including those that are currently disabled. [DISABLED_TOOLS] must be a JSON array of tool names that are currently off-limits. [FALLBACK_TOOL] is the name of a single, always-available tool that can provide a degraded response. Before deploying, validate that your application layer can parse the is_fallback boolean and the user_message string, and ensure that the execution harness enforces the disabled-tool list at the infrastructure level as a secondary guard. In high-risk production environments, log every instance where is_fallback is true to monitor the frequency of degraded service.
Prompt Variables
Placeholders required by the Dynamic Tool Disablement Prompt Under Load. Each variable must be populated at runtime from operational state before the prompt is assembled and sent to the model.
| Placeholder | Purpose | Example | Validation Notes |
|---|---|---|---|
[DISABLED_TOOL_LIST] | Array of tool names currently disabled due to overload, degradation, or maintenance | ["billing_lookup", "fraud_score"] | Must be a JSON array of strings. Empty array allowed. Validate against registered tool names; unknown tool names should log a warning but not block assembly. |
[AVAILABLE_TOOL_SCHEMAS] | JSON array of tool definitions that remain eligible for selection | [{"name": "account_summary", "description": "...", "parameters": {...}}] | Must be valid JSON matching the tool schema contract. Each entry requires name, description, and parameters fields. Schema parse failure must abort prompt assembly. |
[USER_INTENT] | The original user request or intent description requiring tool execution | "I need to check my last three transactions" | Free-text string. Must be non-empty. Sanitize for prompt injection patterns before insertion. Length should be capped at 2000 characters to avoid context overflow. |
[OPERATIONAL_CONTEXT] | Current load conditions, degradation status, and reason for tool disablement | "billing_lookup disabled due to p99 latency exceeding 2s threshold" | String or null. When null, the prompt should still function with a default 'no degradation reported' message. Avoid leaking internal hostnames or IP addresses. |
[USER_FACING_MESSAGE_TEMPLATE] | Template for generating the user-facing explanation when a preferred tool is disabled | "The {tool_name} service is temporarily unavailable. Using {fallback_tool} instead." | String with optional {tool_name} and {fallback_tool} placeholders. Validate that the template contains at least one of these tokens. Null allowed if no user messaging is required. |
[FALLBACK_PRIORITY_ORDER] | Ordered list of tool categories or names to prefer when the primary tool is disabled | ["cached_account_data", "recent_transactions_cache", "generic_lookup"] | Must be a JSON array of strings. Order matters. Each entry should map to a tool in [AVAILABLE_TOOL_SCHEMAS]. Missing entries should trigger a warning. |
[OUTPUT_SCHEMA] | Expected JSON structure for the tool selection decision | {"selected_tool": "string", "disabled_tool_avoided": "string | null", "user_message": "string | null", "confidence": 0.0-1.0} | Must be a valid JSON Schema or example object. Parse check required. The schema must include selected_tool, disabled_tool_avoided, and user_message fields at minimum. |
Implementation Harness Notes
How to wire the Dynamic Tool Disablement Prompt into a production application with validation, retries, and observability.
This prompt is designed to sit inside a tool dispatch layer, not as a standalone chat interaction. The application should maintain a live list of disabled tools—populated by circuit breakers, deployment rollbacks, or manual SRE toggles—and inject that list into the prompt's [DISABLED_TOOLS] placeholder at request time. The model never sees the raw infrastructure state; it only receives the sanitized list of tool names it must avoid. This separation ensures that internal degradation signals (e.g., 'payment-service-circuit-open') do not leak into user-facing responses or model reasoning.
Integration flow: 1) The application receives a user request and fetches the current disabled-tool set from a short-lived cache (TTL < 30 seconds). 2) The prompt is assembled with [DISABLED_TOOLS] as a JSON array of tool names and [AVAILABLE_TOOLS] as the full tool schema list. 3) The model returns a structured JSON object containing selected_tool, arguments, fallback_tool, and user_message. 4) A post-generation validator checks that selected_tool is not present in the disabled list—if it is, the response is rejected and a retry is triggered with an augmented error message. 5) The user_message field is rendered to the end user only after validation passes, ensuring no internal tool names or degradation details are exposed.
Retry and fallback logic: Implement a maximum of two retries. On the first retry, append a system-level instruction: 'Your previous selection [TOOL_NAME] is disabled and unavailable. Choose a different tool from the available set.' On the second failure, bypass the model entirely and route to a pre-configured static fallback (e.g., a cached response or a 'service temporarily limited' message). Log every retry with the disabled-tool list, model selection, and validator result for post-incident review. Model choice: Use a model with strong function-calling discipline (e.g., GPT-4o, Claude 3.5 Sonnet) and set temperature=0 to minimize selection variance under load. Observability: Emit structured logs containing disabled_tools_hash, selected_tool, validation_passed, retry_count, and fallback_activated so SRE dashboards can track degradation impact and model compliance in real time.
Expected Output Contract
Defines the required fields, types, and validation rules for the structured output produced by the Dynamic Tool Disablement Prompt. Use this contract to parse and validate the model's response before routing or executing any tool.
| Field or Element | Type or Format | Required | Validation Rule |
|---|---|---|---|
selected_tool | string | null | Must be a non-empty string matching an active tool name if a tool is selected; must be null if no suitable active tool exists. | |
tool_arguments | object | null | If selected_tool is not null, must be a valid JSON object matching the selected tool's parameter schema. Must be null if selected_tool is null. | |
disabled_tool_avoided | boolean | Must be true. Validation must confirm that selected_tool does not appear in the [DISABLED_TOOL_LIST] provided in the prompt. | |
fallback_applied | boolean | Must be true if the initially preferred tool was in [DISABLED_TOOL_LIST] and an alternative was chosen. Must be false otherwise. | |
user_facing_message | string | Must be a non-empty string. If no tool is selected, must explain the unavailability without exposing internal tool names, disabled lists, or operational state. If a fallback is applied, must not mention the disabled tool. | |
confidence_score | number | If present, must be a float between 0.0 and 1.0 inclusive. Represents the model's confidence in the tool selection. Null is allowed. | |
requires_human_approval | boolean | Must be true if no active tool can satisfy the request and the user-facing message suggests escalation. Must be false otherwise. |
Common Failure Modes
When a dynamic tool disablement prompt runs under load, the most dangerous failures are silent: the model ignores the disabled list, leaks internal state, or selects a degraded tool without telling the user. These cards cover the failure modes that hit first in production and the guardrails that catch them before they cause incidents.
Disabled Tool Still Selected
What to watch: The model selects a tool that appears in the disabled-tool list, either because the list was truncated in a long context window, the model hallucinated a tool name not in the schema, or the disabled list was injected too late in the prompt assembly. Guardrail: Place the disabled-tool list immediately before the tool schema block with an explicit instruction: 'The following tools are currently unavailable and MUST NOT be called under any circumstances.' Validate the selected tool against the disabled list in the harness before execution, not after.
Internal Degradation State Leaked to Users
What to watch: The model explains why a tool is disabled by repeating internal operational details such as 'Tool X is disabled because the payments service is down in us-east-1' or 'rate limit exceeded for premium tier.' This exposes infrastructure topology and incident state to end users. Guardrail: Provide a user-facing fallback message template in the prompt: 'If a requested action requires a currently unavailable tool, respond only with: [USER_FALLBACK_MESSAGE]. Do not mention which tool is disabled or why.' Validate output with a regex or classifier that flags infrastructure terms.
Silent Fallback Without User Disclosure
What to watch: The model routes around a disabled tool by selecting a lower-quality alternative without telling the user that the primary tool is unavailable. The user receives degraded results with no indication that the experience is degraded. Guardrail: Require the prompt to include a disclosure rule: 'If you select a fallback tool because the preferred tool is disabled, you MUST prepend your response with [DEGRADED_SERVICE_DISCLOSURE].' Test for disclosure presence in eval when the primary tool is in the disabled list.
Disabled List Parsed Incorrectly Under Load
What to watch: When the disabled-tool list is long or formatted as a raw JSON array, the model misparses tool names due to punctuation, whitespace, or partial name matches. A tool named 'payment_capture' might not match 'payments_capture' in the disabled list. Guardrail: Normalize tool names to exact string-match identifiers before injection. Use a simple comma-separated list with exact tool names: 'DISABLED_TOOLS: tool_a, tool_b, tool_c.' Add a harness check that confirms the disabled list is a subset of the available tool names and rejects the prompt assembly if any disabled tool is not recognized.
Race Condition on Disabled List Update
What to watch: The disabled-tool list is updated by an operational system while a request is in flight. The model uses a stale list, selects a tool that was just disabled, and the execution layer rejects it—but the user-facing response was already partially formed. Guardrail: Include a version or timestamp in the disabled-tool list payload and instruct the model to echo it in the tool selection audit field. The execution harness compares the echoed version against the current live version and aborts with a retry if they differ. This prevents stale-list execution.
All Candidate Tools Disabled With No Escalation Path
What to watch: The disabled list covers every tool that could satisfy the user intent. The model either hallucinates a non-existent tool, selects a disabled tool anyway, or returns an unhelpful generic error. Guardrail: Add an explicit 'no-available-tool' instruction: 'If all tools that could fulfill this request are in the disabled list, respond with [NO_AVAILABLE_TOOL_MESSAGE] and set the tool_call field to null.' The harness should detect this condition and trigger an escalation workflow to an on-call or human review queue rather than leaving the user stranded.
Evaluation Rubric
Criteria for testing the Dynamic Tool Disablement Prompt Under Load before production deployment. Each row targets a specific failure mode common to overload scenarios.
| Criterion | Pass Standard | Failure Signal | Test Method |
|---|---|---|---|
Disabled Tool Avoidance | Output never selects a tool present in the [DISABLED_TOOLS] list | Tool name from [DISABLED_TOOLS] appears in the final selection or fallback chain | Run 100 test cases with randomized disabled lists; assert zero selections intersect the disabled set |
Fallback Routing Correctness | When the best-fit tool is disabled, the prompt selects the next-best enabled tool from [AVAILABLE_TOOLS] | Prompt returns null, refuses to answer, or selects a tool with no semantic fit to [USER_INTENT] | Inject disabled primary tool; validate the selected alternative is in [AVAILABLE_TOOLS] and matches intent via LLM-as-judge |
User-Facing Message Safety | Response to user contains no internal state, disabled-tool names, or overload indicators | Message includes phrases like 'tool X is disabled', 'system overloaded', or raw [DISABLED_TOOLS] content | Semantic scan of user_message field for leaked operational terms; flag any match against disabled tool names |
Empty Disabled List Handling | When [DISABLED_TOOLS] is empty, prompt selects the best-fit tool without degradation | Selection quality drops compared to baseline prompt with no disablement logic | Compare tool selection accuracy against a no-disablement control prompt across 50 standard cases |
All Tools Disabled Handling | When [DISABLED_TOOLS] covers all [AVAILABLE_TOOLS], prompt returns a graceful degradation message and no tool call | Prompt hallucinates a tool, calls a disabled tool, or returns an unhelpful error | Set [DISABLED_TOOLS] equal to [AVAILABLE_TOOLS]; assert tool_call is null and user_message is non-empty and polite |
Latency Budget Adherence | Prompt processing and tool selection complete within the [LATENCY_BUDGET_MS] constraint | End-to-end selection time exceeds budget by more than 10% under load | Benchmark with concurrent requests at 80% system capacity; measure p95 selection latency |
Partial Disablement Consistency | Same [USER_INTENT] with same [DISABLED_TOOLS] produces the same fallback tool across 5 repeated runs | Selection flips between different fallback tools on repeated identical inputs | Run identical input 5 times with temperature 0; assert single unique tool selection result |
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Adapt This Prompt
How to adapt
Start with the base prompt and a hardcoded [DISABLED_TOOLS] list. Use a simple string array and instruct the model to exclude any tool whose name appears in that list. Skip structured output validation and focus on whether the model avoids disabled tools in a few manual test cases.
codeYou are a tool router. The following tools are currently disabled and must not be called: [DISABLED_TOOLS]. User intent: [USER_INTENT] Available tools: [TOOL_LIST] Select the best available tool that is not in the disabled list.
Watch for
- The model calling a disabled tool when the name is slightly different (e.g.,
search_v2vssearch) - No fallback behavior when all tools are disabled
- The model mentioning disabled tools in its reasoning but still avoiding them in the final call

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.
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