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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description still adds real value beyond them: the 'Free' cost signal is meaningful in a sibling set containing buy_file_x402 payment tools, and it discloses the shape of the returned counts rather than just saying 'search'.

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. The cost qualifier is front-loaded and the return contents are packed into one clause; nothing could be cut without losing routing or result information.

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 usefully enumerates what comes back, and annotations cover the safety profile, which is adequate for a one-parameter search. It omits any mention of result limits or pagination, the only real gap.

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% and there is a single required parameter whose accepted forms (name, URN, GIAS group UID) are documented in the schema itself. The description's id-prefix notation is output-oriented and only loosely reinforces the query formats, so the 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 ('Find') and resource ('buyer ids') scoped to English schools, trusts and councils, then enumerates exactly what each result carries (published edtech contracts, renewals, live tenders, trust changes). The id formats (school:<URN>, trust:<UID>, org:<slug>) make it distinguishable from the sibling school_renewals and school_buyer_brief at a glance.

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?

Explicitly routes the agent: 'Use before school_buyer_brief' names the sibling and the sequencing condition. It gives no when-not guidance or alternatives for the non-brief siblings, so it stops short of a 5.

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