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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable behavioral context beyond this by disclosing pricing ($0.01/call), payment method (x402 on base), and the free/no-key nature of GLEIF data, plus the optional API key requirement. No contradictions with annotations.

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 compact, with two sentences plus a pricing note. It front-loads the core value proposition and includes only essential details, making it easy to parse quickly. Every sentence earns its place.

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 moderate complexity (3 params, 1 required, no output schema) and rich annotations, the description covers key aspects: input types, optional enrichment, pricing, and auth needs. It is complete enough for an agent to use it correctly, though it could mention limits (e.g., 100 max) which are in the schema but not the description.

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%, so the baseline is 3. The description itself mentions the accepted identifier formats and the optional Companies House key, but the schema already provides detailed parameter descriptions (e.g., pipe syntax for country hints). The description adds little beyond what the schema already communicates.

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 clearly states the tool turns a company name, LEI or UK company number into an official registry card, listing the specific output fields (legal name, status, jurisdiction, registered address, LEI). It also distinguishes itself from siblings by naming GLEIF and options UK Companies House enrichment, making its purpose unmistakable.

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 provides clear context for when to use the tool: for official registry data via GLEIF with no key, and optionally for UK directors/SIC codes with a Companies House key. It does not explicitly exclude alternatives (e.g., company-lookup) or state 'use when...', but the context is sufficiently clear for an agent to select it appropriately.

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