Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With annotations already establishing readOnlyHint=true, idempotentHint=true, and destructiveHint=false, the description adds substantial behavioral context: cascading internal lookups, graceful degradation when GLEIF/OpenFIGI are unavailable, explicit `unresolved` fields, source-labelled identifiers, and multi-match behavior returning figi_candidates. This goes well beyond what the annotations provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but front-loaded with human-language triggers and a clear 'Use FIRST' directive. While dense and information-rich, some redundancy exists around supported identifiers and fallback behavior, so it is not maximally concise. Still, each section earns its place given the tool's complexity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with no output schema, the description explains return-level behavior sufficiently: RxCUI plus ingredient and brand with citation for drugs, figi_candidates for ambiguous securities, source-labelled identifiers, and explicit unresolved fields. Combined with complete parameter documentation and annotations, an agent can correctly invoke this tool and interpret results.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Even though schema description coverage is 100%, the description adds critical semantic guidance: pass the entity name only, never the full noun phrase, use issuer name exactly as printed for bonds, and accept ticker, CIK, ISIN, or company name. The value parameter's ambiguity is resolved with concrete examples and failure-mode explanations that the schema alone would not convey.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a clear, specific purpose: resolve a user-spoken NAME to canonical/official identifiers that other tools require as input. It distinguishes itself by explicitly saying 'Use FIRST whenever you have a name but need an ID' and enumerates supported entity types with concrete identifier examples, making it easy to tell apart from siblings like entity_profile or compare_entities.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly says to use this tool first whenever a name is present but an ID is needed, which is strong contextual guidance. It also details how to handle ambiguous matches via figi_candidates and which inputs are accepted. However, it does not directly contrast itself with sibling tools like entity_profile or validate_claim, so the when-not-to-use guidance is not fully explicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.