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

Annotations already mark the tool as read-only and idempotent, and the description adds substantial behavioral context beyond that: cascading internal lookups, graceful degradation when GLEIF/OpenFIGI are unavailable, explicit `unresolved` fields, and `figi_candidates` when a name matches multiple instruments. This gives the agent an accurate model of edge-case behavior.

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 information-dense, with clearly separated sections for supported types and usage. Almost every sentence carries unique detail (cascading lookups, non-equity resolution, unresolved fields). Some parentheticals are verbose, but the structure is logical and front-loaded with intent and usage priority.

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?

With no output schema, the description must explain return behavior, and it does: identifiers are labelled with sources, unresolved identifiers are stated explicitly, and multi-match cases return `figi_candidates`. It also covers edge cases like non-US issuers, non-equity instruments, and graceful degradation. This is sufficient for an agent to call the tool correctly 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?

Schema description coverage is 100% and the value parameter already has rich detail. The description adds one meaningful piece beyond the schema: company input also accepts ISIN, which the schema's value description omits. It also reinforces the 'entity name only' rule and trailing-word warning, but most semantic weight is already in the schema.

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 uses a specific verb+resource construction: 'resolve a user-spoken NAME to the canonical/official identifiers other tools require as input.' It distinguishes itself from siblings by explicitly positioning itself as the first tool to try when you have a name but need an ID, with supported types and examples.

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 gives explicit context for use: 'Use FIRST whenever you have a name but need an ID.' It also enumerates supported entity types and input forms. However, it does not explicitly state when not to use this tool or name alternatives such as entity_profile or compare_entities, so it stops short of full when/when-not guidance.

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