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

Even with readOnly/idempotent annotations, the description goes well beyond them: it explains multi-match ambiguity (returns figi_candidates, asserts nothing), explicit unresolved listing, graceful degradation when GLEIF/OpenFIGI is unavailable, and ISIN-to-legal-entity mapping. It also discloses the internal cascade of lookups and that enrichment is best-effort.

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 but front-loaded with purpose and trigger phrases, then organized by supported type. Some parenthetical clauses are lengthy, but nearly every sentence adds behavioral or routing value; the slight over-length keeps it from a perfect 5.

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 carries the full burden of explaining return semantics and does so thoroughly: identifiers per type, source labelling, unresolved handling, figi_candidates, degradation, and input formats. Nothing essential is missing for an agent to call this tool correctly.

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 substantially enriches both parameters: it explains what each entity type resolves to and, for value, gives exact formatting rules (entity name only, bond issuer as printed, never trailing security-class words). This goes well beyond the schema descriptions.

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-phrase triggers and a clear verb+resource: resolving a spoken name to canonical/official identifiers. It defines the two supported types and explicitly positions itself as the input provider for other tools, separating it from siblings like entity_profile or compare_entities even without naming them.

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 explicit guidance: 'Use FIRST whenever you have a name but need an ID,' plus trigger phrases and supported type details. It does not, however, name specific alternatives or state when not to use it, so it stops short of full when/when-not routing.

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