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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description goes well beyond that: it explains graceful degradation (EDGAR identifiers still return if GLEIF/OpenFIGI is down), cascading internal lookups, ambiguous-match behavior (returns `figi_candidates` and asserts nothing), and explicit `unresolved` listing for missing identifiers. These are non-obvious behaviors an agent must know, and they are not present in annotations. No contradiction.

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 it is front-loaded with examples and structured into a clear flow: usage phrasings, 'Use FIRST', supported types with detailed behaviors, and graceful-degradation notes. Every sentence adds operational value for a complex tool. It is not tautological or wasteful, though it could be tightened slightly without losing meaning. A 4 reflects that it's appropriately sized for the complexity but not minimal.

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?

Given the tool's complexity (two entity types, multiple identifier sources, edge cases like non-equity instruments and ambiguous names), the description is remarkably complete. It covers what happens on unmatched names, multiple matches, unavailable external sources, and the exact format for bond issuers. Nothing an agent needs to call this tool correctly is missing, and it even provides background on why certain behavior is correct.

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% (both parameters described), so the baseline is 3. But the description adds substantial meaning: for `value`, it clarifies that a bond's value should be the issuer exactly as printed, not the full noun phrase, and that an ISIN resolves to the legal entity. For `type`, it explains the exact identifier sets each type returns. This goes far beyond the schema's simple enum, guiding correct input formatting.

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 opens with concrete user phrasings ('What's the ticker for…', 'find the CIK for…') and states the core purpose: resolving a name to canonical identifiers other tools require. It names the specific identifier types per entity type (CIK, ticker, LEI, FIGI for company; RxCUI for drug) and explicitly says 'Use FIRST whenever you have a name but need an ID', which clearly differentiates it 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?

It gives a crisp rule: 'Use FIRST whenever you have a name but need an ID.' It also explains when to choose company vs. drug and warns against passing full noun phrases for bonds. It doesn't name specific alternative tools, but the 'use FIRST' instruction is strong enough to route an agent, and it notes that the tool replaces 2-3 manual lookups, clarifying its role in the workflow.

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