This prompt is for agent platform engineers and tool-integration developers who need to recover from an agent loop that has called a non-existent or misspelled tool. The job-to-be-done is to map an incorrect tool name to the closest valid entry in a provided tool registry, preventing a hard failure in the agent's execution. The ideal user is someone building a resilient agent harness who needs an automated, inline repair step before escalating to a human or aborting the task. Required context includes the exact incorrect tool name the model produced, the full list of available tool names and their descriptions, and the recent conversation or reasoning trace that led to the invalid call.
Prompt
Tool Name Correction and Disambiguation Prompt Template

When to Use This Prompt
Define the job, reader, and constraints for the Tool Name Correction and Disambiguation Prompt Template.
Do not use this prompt when the tool name is correct but the arguments are malformed—that is a job for a parameter repair prompt. It is also unsuitable when the agent's intent is fundamentally ambiguous and requires clarification from a user; this prompt is for disambiguation against a known registry, not for resolving vague user requests. This prompt assumes a single incorrect tool name as input. If the model hallucinated an entirely new workflow that has no semantic match in the registry, the fuzzy-match confidence will be low, and the correct behavior is to escalate, not to force a match. The harness should enforce a minimum confidence threshold before accepting the correction.
Before wiring this into your agent loop, ensure your tool registry is complete and that each tool has a clear, descriptive purpose string. The prompt's effectiveness depends on semantic similarity between the incorrect name and the registry descriptions. Test the prompt with common failure modes from your logs: misspellings, aliases from other platforms, and tool names the model might confabulate. After implementing, monitor the correction_confidence score and the rate of escalations to verify the prompt is reducing manual interventions without introducing silent misroutings.
Use Case Fit
Where the Tool Name Correction and Disambiguation Prompt Template works well, where it breaks down, and the operational preconditions for safe deployment.
Good Fit: Fuzzy Name Recovery
Use when: the model calls a tool that doesn't exist in the registry, but the intended target is clear from context or a close string match. Guardrail: require a minimum fuzzy-match confidence score before accepting the correction; log all corrections for registry hygiene review.
Bad Fit: Ambiguous Registry
Avoid when: multiple tools share similar names or functionality, making disambiguation impossible without user clarification. Guardrail: if the top match score is below a defined threshold or the gap between the top two candidates is too narrow, escalate to the agent for clarification instead of guessing.
Required Inputs
Must have: the incorrect tool name as called by the model, the full tool registry with names and descriptions, and the invocation context (user intent, conversation history). Guardrail: validate that the registry snapshot used for correction matches the version available at invocation time to prevent stale-reference errors.
Operational Risk: Silent Wrong-Tool Execution
Risk: the correction maps to a valid but semantically wrong tool, causing side effects without the agent or user noticing. Guardrail: for tools with write or destructive capabilities, require a confirmation step or dry-run before executing the corrected call.
Operational Risk: Registry Drift
Risk: tools are added, removed, or renamed between correction and execution, invalidating the repair. Guardrail: version the tool registry and include the version in the correction prompt; re-validate the corrected tool name against the live registry before execution.
Escalation Path
Risk: the correction loop consumes retry budget without resolving the ambiguity. Guardrail: after a configured number of failed disambiguation attempts, stop retrying and escalate to a human operator or a higher-capability model with the full context and match candidates.
Copy-Ready Prompt Template
A reusable prompt for mapping an incorrect or misspelled tool name to the closest match in your tool registry.
This prompt template is the core instruction set for recovering from a failed tool call where the model requested a tool that doesn't exist. It takes the incorrect name, the full list of available tools with their descriptions, and the original user intent, then returns the best match along with a confidence score. The template is designed to be copied directly into your agent's error-recovery loop, with square-bracket placeholders you replace with runtime values from your tool registry and execution context.
textYou are a tool name disambiguation system. Your job is to map an incorrect or misspelled tool name to the closest matching tool in the available tool registry. ## INPUT - Incorrect tool name: [INCORRECT_TOOL_NAME] - User's original request or agent context: [USER_CONTEXT] - Available tools (name and description): [AVAILABLE_TOOLS_LIST] ## TASK 1. Compare the incorrect tool name against every available tool name and description. 2. Identify the single best match using: - Edit distance (typos, character swaps, missing characters) - Semantic similarity (synonyms, alternate phrasings, related concepts) - Functional fit (does the tool's described purpose match what the user was trying to do?) 3. If no tool is a reasonable match, return a "no_match" result. ## OUTPUT SCHEMA Return ONLY valid JSON with this exact structure: { "matched_tool": "<exact tool name from registry or null>", "confidence": <float between 0.0 and 1.0>, "rationale": "<brief explanation of why this match was chosen or why no match exists>", "requires_escalation": <boolean> } ## CONSTRAINTS - [CONFIDENCE_THRESHOLD]: If confidence is below this value, set requires_escalation to true. - [MAX_CANDIDATES_TO_CONSIDER]: Limit fuzzy matching to this many top candidates before detailed comparison. - [ESCALATION_ACTION]: When escalation is required, include this recommended action in the rationale. - Never invent tool names. Only return names exactly as they appear in the available tools list. - If the incorrect name could plausibly match multiple tools, choose the one with the strongest functional fit to the user context.
To adapt this template, replace the square-bracket placeholders with runtime data from your agent loop. [INCORRECT_TOOL_NAME] comes from the failed function call. [USER_CONTEXT] should include the original user message and any preceding agent reasoning to provide functional fit signals. [AVAILABLE_TOOLS_LIST] must be a complete dump of your tool registry—include both the tool name and its description for each entry, as semantic matching depends on descriptions. Set [CONFIDENCE_THRESHOLD] based on your risk tolerance (0.7 is a common starting point). Wire [ESCALATION_ACTION] to your human review queue or a clarification prompt that asks the user to specify the intended tool. Before deploying, run this prompt against a golden set of known misspellings, aliases, and completely absent tool names to calibrate your confidence threshold and catch false-positive matches.
Prompt Variables
Required inputs for the Tool Name Correction and Disambiguation Prompt. Each placeholder must be populated before the prompt is assembled and sent to the model.
| Placeholder | Purpose | Example | Validation Notes |
|---|---|---|---|
[INCORRECT_TOOL_NAME] | The misspelled, aliased, or non-existent tool name the model attempted to call. | get_weather_forcast | Must be a non-empty string. Check that it is not already a valid tool name in the registry to avoid false-positive corrections. |
[TOOL_REGISTRY_JSON] | A JSON array of available tool definitions, including name, description, and parameter schema for each tool. | [{"name": "get_weather_forecast", "description": "...", "parameters": {...}}] | Must be valid JSON. Validate that every object has a non-empty name and description field. Schema check required before prompt assembly. |
[INVOCATION_CONTEXT] | The user's original request or the agent's reasoning that led to the incorrect tool call. Provides semantic grounding for disambiguation. | User asked: 'What's the weather like tomorrow in Berlin?' | Must be a non-empty string. If the context is missing, set to null and note that disambiguation accuracy will degrade. |
[FUZZY_MATCH_THRESHOLD] | A float between 0.0 and 1.0 that sets the minimum similarity score for a candidate match to be considered valid. | 0.75 | Must be a number. Clamp to [0.0, 1.0]. If below 0.5, expect high false-positive rates. If above 0.95, expect high false-negative rates. |
[MAX_CANDIDATES] | The maximum number of candidate tool names to return in the disambiguation output. | 3 | Must be a positive integer. If set to 1, the prompt should still return a confidence score. If set to 0, the prompt should escalate immediately. |
[ESCALATION_POLICY] | A short instruction defining when to escalate to a human or abort instead of guessing. Injected as a constraint into the prompt. | If no candidate exceeds the fuzzy match threshold, return an escalation request instead of a guess. | Must be a non-empty string. Check that the policy does not contradict the fuzzy match threshold or max candidates settings. |
Implementation Harness Notes
How to wire the tool name correction prompt into an agent loop with fuzzy matching, confidence scoring, and escalation logic.
This prompt is designed to be called as a recovery step inside an agent execution loop when a tool call fails with a 'tool not found' or similar error. The harness should intercept the failure, extract the incorrect tool name and the full list of available tools from the agent's tool registry, and invoke this prompt before retrying the action. Do not use this prompt for initial tool selection; it is strictly a post-failure correction mechanism. The primary integration point is the error handler of your agent's tool execution layer—whether that's a LangChain tool executor, a custom ReAct loop, or an MCP client.
To wire this in, build a tool_name_correction function that accepts three arguments: incorrect_name (the name the model tried to call), available_tools (a list of tool definition objects including name, description, and parameter schemas), and context (the last N messages of the conversation or agent trace). Populate the prompt's [INCORRECT_TOOL_NAME], [AVAILABLE_TOOLS_JSON], and [CONVERSATION_CONTEXT] placeholders with these values. The model will return a JSON object with corrected_name, confidence_score, and reasoning. Your harness must parse this output and apply a configurable confidence threshold—we recommend starting at 0.85 for automatic correction and routing anything below that to a human review queue or a clarification prompt back to the agent. Log every correction attempt with the original name, corrected name, confidence score, and whether the correction was accepted or escalated. This log becomes your primary observability surface for tool naming drift and model confusion patterns.
For the fuzzy-match fallback, implement a secondary validation layer in your harness that runs even if the model returns a high-confidence correction. Take the corrected_name and perform an exact case-insensitive match against your tool registry. If no exact match exists, fall back to a Levenshtein distance or token-sort-ratio check against all registered tool names, and select the closest match above a similarity threshold of 0.8. If both the model correction and the fuzzy fallback fail, escalate the failure to the agent's error policy—do not silently substitute a tool. This dual-layer approach prevents the model from hallucinating tool names that don't exist while still recovering from common misspellings and aliases. For production deployments, instrument the harness with metrics: correction attempt rate, confidence score distribution, fuzzy-match fallback rate, and escalation rate. These metrics will tell you whether your tool naming conventions need adjustment or whether the model requires fine-tuning on your specific tool registry.
Expected Output Contract
Defines the structured payload returned by the Tool Name Correction and Disambiguation prompt. Use this contract to validate the repair output before routing it to the agent's tool execution layer.
| Field or Element | Type or Format | Required | Validation Rule |
|---|---|---|---|
corrected_tool_name | string | Must exactly match a tool name in the provided [TOOL_REGISTRY]; case-sensitive comparison required | |
original_input_name | string | Must equal the [INCORRECT_TOOL_NAME] input; no modification allowed | |
match_confidence | float | Must be between 0.0 and 1.0 inclusive; parse check as float; values below [CONFIDENCE_THRESHOLD] should trigger escalation | |
match_method | enum | Must be one of: exact_match, fuzzy_match, semantic_match, manual_override; reject any other value | |
alternative_candidates | array of objects | If present, each object must contain tool_name (string) and confidence (float); array must not include the corrected_tool_name | |
escalation_required | boolean | Must be true if match_confidence < [CONFIDENCE_THRESHOLD] or if multiple candidates exceed the threshold; otherwise false | |
disambiguation_reasoning | string | Must be non-empty; should reference specific tool descriptions or invocation context from [TOOL_REGISTRY] and [INVOCATION_CONTEXT] | |
repair_timestamp | ISO 8601 | Must parse as valid ISO 8601 datetime; must be within 5 seconds of system time at validation check |
Common Failure Modes
What breaks first when correcting tool names and how to guard against it.
Ambiguous Matches Cause Wrong Tool Selection
What to watch: The model maps a misspelled tool name to the wrong tool because two available tools have similar names or overlapping descriptions. This is common when tool registries contain create_order and create_order_item, or search_users and search_user_groups. Guardrail: Require the prompt to output a confidence score and a ranked list of candidates. If the top two scores are within a configurable threshold (e.g., 0.15), escalate to a human or a clarification step instead of auto-selecting.
Fuzzy Matching Overcorrects Intentional Variants
What to watch: A user or upstream agent intentionally uses a deprecated or alias tool name that maps to a specific legacy workflow. The repair prompt overcorrects it to the current canonical name, breaking the intended behavior. Guardrail: Maintain an explicit alias map in the prompt context. Instruct the model to check the alias map before applying fuzzy matching. If a match is found in the alias map, use the mapped canonical name without scoring.
Missing Context Leads to Hallucinated Tool Names
What to watch: The repair prompt receives only the incorrect tool name without the surrounding invocation context or conversation history. It hallucinates a plausible but incorrect tool name that doesn't exist in the registry. Guardrail: Always include the full tool call payload and the preceding conversation turn in the repair prompt. Validate the corrected tool name against the registry before returning it. If the corrected name isn't in the registry, flag as a hallucination and escalate.
Registry Drift Causes Stale Corrections
What to watch: The tool registry used in the repair prompt is outdated. The model corrects a name to a tool that has been renamed, deprecated, or removed, causing a secondary failure downstream. Guardrail: Version the tool registry and include a last_updated timestamp in the repair prompt context. Add a post-repair validation step that checks the corrected name against the live registry before execution. Log mismatches for registry sync alerts.
Confidence Scoring Is Poorly Calibrated
What to watch: The model assigns high confidence to an incorrect correction, or low confidence to a correct one. This causes either false-positive auto-executions or unnecessary escalations. Guardrail: Calibrate confidence thresholds against a golden dataset of known misspellings and their correct mappings. Track precision and recall per threshold. Implement a human-review sampling loop for corrections near the threshold to continuously recalibrate.
Repair Loop Causes Infinite Retries
What to watch: The repair prompt corrects a tool name, but the corrected name still fails validation or execution. The agent loop retries the repair, which produces the same incorrect correction, creating an infinite loop. Guardrail: Implement a retry budget with a maximum of 2 repair attempts. On the second failure, log the original name, the attempted corrections, and the registry state. Escalate to a human operator and abort the agent loop for that turn.
Evaluation Rubric
Use this rubric to evaluate the quality of a tool name correction before allowing the agent loop to proceed. Each criterion should be tested programmatically or via LLM-as-a-judge before shipping.
| Criterion | Pass Standard | Failure Signal | Test Method |
|---|---|---|---|
Corrected Tool Name Exists in Registry | Output tool name exactly matches a key in [TOOL_REGISTRY] | Output name is not found in the registry or is a hallucinated name | Exact string match against [TOOL_REGISTRY] keys |
Fuzzy Match Confidence Above Threshold | Confidence score for the match is >= [CONFIDENCE_THRESHOLD] | Score is below threshold or the model cannot produce a numeric score | Parse numeric score from output and assert >= [CONFIDENCE_THRESHOLD] |
No Ambiguous Multi-Match Without Resolution | If multiple tools are within the confidence threshold, output must include a ranked list with tie-breaking rationale | Output returns a single tool when multiple are equally likely, or returns an unranked list | Check for ranked list structure when edit distance or embedding similarity is tied |
Original Incorrect Name Preserved for Audit | Output includes the original [INCORRECT_TOOL_NAME] in an audit field | Original name is missing, rewritten, or silently corrected without trace | Schema check for non-null audit field containing the exact input string |
Disambiguation Rationale Is Grounded | Rationale references specific fields from the tool schema or invocation context | Rationale is generic, hallucinates tool capabilities, or ignores [INVOCATION_CONTEXT] | LLM-as-a-judge check: rationale must cite at least one concrete schema field or context element |
Escalation Triggered When No Match Found | Output returns a structured escalation object when no tool meets the confidence threshold | Output forces a low-confidence match or returns null without escalation | Assert escalation object exists and contains original name and registry snapshot |
Output Schema Is Valid and Complete | Output conforms to [OUTPUT_SCHEMA] with all required fields present and correctly typed | Missing required fields, extra hallucinated fields, or type mismatches | JSON Schema validation against [OUTPUT_SCHEMA] |
Latency Within Retry Budget | Correction completes within [MAX_LATENCY_MS] to avoid agent loop timeout | Correction exceeds latency budget, risking agent loop stall | Measure wall-clock time from prompt submission to parsed output |
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Adapt This Prompt
How to adapt
Start with the base prompt and a static tool registry. Use exact string matching for the initial disambiguation pass before invoking the LLM. Keep the fuzzy-match confidence threshold low (e.g., 0.6) to surface more candidates for manual review.
code[INCORRECT_TOOL_NAME]: [INPUT] [AVAILABLE_TOOLS]: [TOOL_REGISTRY_JSON] [CONVERSATION_CONTEXT]: [LAST_N_MESSAGES] Return the closest matching tool name and a confidence score.
Watch for
- Over-matching short tool names to unrelated tools
- Confidence scores that don't correlate with actual correctness
- Missing edge cases where two tools are equally close matches

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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