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

The description goes far beyond the readOnly/idempotent/non-destructive annotations by disclosing concrete behaviors: ambiguous name matches return `figi_candidates` without asserting a single answer, unresolved identifiers are explicitly listed under `unresolved`, LEI/FIGI enrichment degrades gracefully when upstream sources are unavailable, and identifiers carry source labels. This is rich, non-obvious behavioral context that annotations alone do not 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 dense and front-loaded with example queries and the primary usage directive, but it is presented as one long paragraph with deep nested parentheticals, making it harder to scan. Most sentences carry useful information, yet the lack of structured formatting and some repetition with the schema's value description keep it from being concise.

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?

Despite having no output schema, the description narrates the return shape: identifiers, source labels, `figi_candidates`, and `unresolved`. It covers input variants, two entity types, edge cases like non-equity instruments, ISIN handling, and degraded downstream availability, so an agent has enough context to invoke the tool correctly in a wide range of name-to-ID 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%, so the baseline is 3, but the description adds meaningful semantics beyond the schema: it enumerates accepted company inputs (ticker, CIK, ISIN, or name), explains how ISINs resolve through GLEIF to legal entities, and details ambiguity behavior. It also clarifies value formatting with examples and the "ENTITY NAME ONLY" warning, going beyond the schema's brief description.

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 explicitly states the tool resolves user-spoken names to canonical/official identifiers and lists concrete example queries ("What's the ticker for…", "find the CIK for…"). It clearly distinguishes itself by saying it produces identifiers that "other tools require as input" and should be used "FIRST" when a name but no ID is available, separating it from siblings like search_entities or entity_profile.

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 phrase "Use FIRST whenever you have a name but need an ID" gives clear, direct usage guidance. It also explains supported entity types and how the tool can replace 2-3 manual lookups, but it does not explicitly name sibling alternatives or state when not to use this tool in favor of another, so it falls just short of full exclusionary guidance.

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