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

Annotations already mark it read-only, open-world, and idempotent, and the description adds substantial behavioral detail beyond that: ambiguous names return figi_candidates rather than asserting false results, unresolved identifiers are listed under unresolved instead of omitted, sources are labeled per identifier, and LEI/FIGI enrichment degrades gracefully when external services are unavailable. No contradiction with annotations exists.

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 front-loaded with purpose and common queries, and most sentences carry useful information. It is quite long and dense, with heavy parentheticals that make scanning more effortful, but the complexity of the tool justifies much of the length.

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 two-parameter tool with no output schema, the description covers input forms, resolution behavior, output fields, ambiguity handling, source labeling, unresolved results, and fallback behavior. An agent has enough context to call the tool correctly and interpret its responses in most cases.

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%, but the description adds critical semantics beyond the schema. It specifies accepted company inputs including ISIN, explains the ISIN-to-LEI resolution path, and gives a crucial usage warning for the value parameter: pass only the entity name as printed, never the full noun phrase, because trailing security-class words will fail FIGI matching.

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 specific verb and resource: resolving user-spoken names to canonical/official identifiers, with concrete query examples. It also names the two supported entity types and distinctly frames the tool as the identity-lookup step before other tools, separating it from siblings like entity_profile and 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 gives an explicit trigger: 'Use FIRST whenever you have a name but need an ID.' It also notes that a single call replaces 2–3 manual lookups, which helps the agent decide when to invoke it. However, it does not explicitly state when not to use it or name alternatives for deeper entity investigation.

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