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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add data semantics — and it does: 'an award offered is not money paid' warns about a real misinterpretation risk. It also names fields returned (funder, licence, source link), which matters because there is no output schema.

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 tight sentences, front-loaded with what the tool returns and followed by the key caveat. Every clause carries information; only the licence/source-link detail feels slightly incidental.

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?

For a 7-parameter, filter-only read tool with no output schema, the description covers resource identity, matching key, and returned fields, plus a critical interpretation caveat. Missing only result-ordering or empty-result behaviour, which is minor here.

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 baseline is 3. The description adds one genuine clarification — that the company parameter is a Companies House number, i.e. the join key — but says nothing extra about funder, since, source, min_award, or pagination beyond what the schema documents.

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 the specific resource ('public grant awards') and the matching key ('matched to a company number'), with a concrete funder example. It is clearly distinguishable from siblings like get_company_financials or get_company_rounds, though it never names an alternative directly.

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?

Usage is only implied: an agent can infer this is the tool for grant funding tied to a company. There is no explicit when-to-use versus get_company_rounds or search_companies, and no statement that all filters are optional or that omitting company returns a broad sweep.

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