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

Goes well past the readOnlyHint/openWorldHint annotations: discloses the rendering residential proxy source, ~20 s typical latency with a recommended 45 s timeout, 20 results per page across pages 1-5, and the x402 pricing model ($0.02 USDC per successful call, failures not charged). These are exactly the cost and timing facts an agent needs before calling.

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?

Front-loads what the tool returns before the operational caveats, and every clause carries information. It is dense — the long field enumeration plus latency/pricing could be split, but nothing is redundant.

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 3-parameter scraping tool with an output schema already present, the description covers everything else an agent must know: data source, pagination limits, latency/timeout, and billing behavior. No relevant gap remains.

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 the baseline is 3, but the description adds meaning the schema lacks: it clarifies that location accepts a town or postcode, caps paging at 20-per-page pages 1-5, and notes the total is returned as a rounded figure like '10,000+'.

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?

Names the specific source (CV-Library UK), the retrieval scope (location plus optional keyword), and enumerates the returned fields, so an agent can distinguish it from sibling UK boards like jobs_reed_co_uk or jobs_gumtree_jobs without opening any schema.

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 UK/CV-Library scoping implies when this tool fits, and 'location and optional keyword' hints at the query shape, but there is no explicit when-to-use/when-not guidance and no named alternative among the many UK-capable siblings. Usage is inferable rather than stated.

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