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

Annotations already declare read-only, idempotent and non-destructive, so the description's job is to add operational behaviour — which it does by disclosing the inclusion rule (only tenders still open, or unstated dates with recent publication) and the ranking order (most relevant first). It does not describe result shape or the practical effect of the limit cap, but the ranking and freshness rules are genuine added context.

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?

Three short sentences, front-loaded with the core action and scope, then coverage sources, then the filtering/ranking rule. No filler and nothing repeated.

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 five-parameter read-only search with a fully documented schema and no output schema, the description supplies the essentials: coverage, open-only constraint, and ordering. It leaves the per-result fields unspecified, which is a minor gap an agent would only notice after calling.

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%, with enum, pattern and range constraints already documented per parameter, so the schema carries the semantics. The description reinforces the source list and the open-only filter but adds no syntax or format detail beyond the schema — the correct baseline of 3.

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 (search) plus resource (open UK public-sector tenders) and names the six portals covered, so an agent immediately knows this is a discovery tool rather than a single-record fetch like get_tender or a portal list like list_sources.

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?

Gives clear context for when the tool applies (keyword discovery of open opportunities) and implicitly scopes out awarded/closed tenders. It stops short of explicitly naming siblings or stating exclusions such as 'use get_tender once you have an ID', so it is clear but not fully routed.

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