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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new operational context – the free-account/sign-in requirement – which the agent needs before calling. It stops short of describing pagination or rate limits, but for a single-record read that is minor.

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?

Two sentences, no filler, and the returned-field list is compact. Minor deduction because the auth prerequisite is placed before the purpose rather than leading with what the tool does.

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?

There is no output schema, so the description's field enumeration usefully compensates by telling the agent what comes back. The auth note covers the main operational surprise; nothing critical is missing for a single-record lookup.

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% and the single parameter is documented in the schema ('Slug or uuid, as returned by the search tools'). The description merely repeats 'slug or uuid' without adding format, resolution order, or error behavior, so baseline 3 applies.

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?

States a specific verb+resource ('One company by slug or uuid') and enumerates what is returned (description, tags, parent, subsidiaries, sponsorships, total editions, last seen date). It does not explicitly name search_companies as the way to obtain the slug/uuid, so sibling differentiation is left implicit.

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 authentication prerequisite ('Requires a free Messe Atlas account (sign in when prompted)') but offers no explicit when-to-use guidance or steering away from search_companies or get_organizer. Usage is only implied by the requirement of a slug/uuid.

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