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

Annotations already mark readOnly, idempotent, and non-destructive, but the description adds critical behaviors: internal cascade across multiple endpoints, graceful degradation when GLEIF/OpenFIGI are unavailable, explicit handling of ambiguous matches (returns figi_candidates), and explicit `unresolved` field for failed lookups. This goes far beyond annotation hints.

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 every sentence earns its place. It's front-loaded with the core purpose and 'Use FIRST', then organized into SUPPORTED TYPES with clear subpoints. The length is justified by the tool's complexity, and the structure guides the reader from generalized use to specific edge cases without redundancy.

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 and 2 parameters, the description is remarkably complete: it explains the return concept (canonical identifiers, unresolved field, figi_candidates), covers all supported entity types, details resolution fallbacks, and even warns about input pitfalls. An agent has everything needed to call it correctly in most scenarios.

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?

Schema coverage is 100% for both parameters, but the description elevates meaning: it explains the `value` parameter's exact formatting rules, warns against including trailing security-class words for bonds, and clarifies how ticker/CIK/ISIN inputs resolve. For `type`, it details what each enum value returns, including the ISIN-to-LEI mapping for non-US issuers. This is substantial added value.

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 is crystal clear: it states the core action ('resolve a user-spoken NAME to the canonical/official identifiers'), gives multiple query examples, and enumerates supported types with specific identifier sources. It distinguishes itself from siblings like entity_profile and compare_entities by focusing on ID resolution as a prerequisite.

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?

Explicit directive 'Use FIRST whenever you have a name but need an ID' provides unambiguous when-to-use. It also spells out edge cases (bonds, non-equity instruments, ambiguous matches) and what to pass vs. what not to pass. While it doesn't name alternative tools, the primary use condition is so specific that an agent is unlikely to misapply it.

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