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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so safety is covered. The description adds value beyond them: it discloses the return payload (titles, short summaries, links) and the empty-query fallback behavior — both things annotations cannot express and that matter since 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?

Three short sentences with the core purpose front-loaded and no filler. 'Some written by trainers listed on the site' is mildly tangential but does hint at cross-linking with trainer content, so it is not wasted.

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 only two optional parameters, full schema documentation and no output schema, the description supplies what structured data cannot: the return shape and the zero-argument behavior. It is close to complete for a simple search tool; only query-strategy guidance is missing.

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 both the limit cap/default and query examples already documented in the schema. The description adds only the no-query case, which the schema does not state, but says nothing about limit semantics. Baseline 3 is appropriate.

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) and a clearly bounded resource (fitness, training and nutrition articles on UK Fitness Pro), plus what is returned. The sibling tools operate on entirely different resources (trainers, locations), so an agent can discriminate without opening the schema, though no sibling is named explicitly.

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 covers one usage case well — 'With no query, returns the latest articles' tells the agent that an empty call is valid and browsing-style. It gives no guidance on when to prefer this over search_trainers/get_trainer_profile, or on how to phrase queries, so usage is only implied.

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