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

Adds substantial context beyond the readOnly/openWorld annotations: a per-call cost of $0.05 paid in USDC on Base via x402, daily refresh cadence, and hard caps of 100 notices and 30 days back. That payment requirement is critical information an agent needs before calling. It stops short of describing pagination or result-shape behavior, so not a 5.

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 dense sentences with no filler: resource and sources first, filter axes second, then the operational constraints (caps, freshness, price). Every clause carries information an agent needs.

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 10-parameter, all-optional tool with no output schema, the description covers the resource, filters, limits, freshness and cost. The remaining gap is what a returned notice looks like in tenders mode versus awards mode, which matters since there is no output schema to fall back on.

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 90%, so the schema already documents nearly every parameter including enums and examples. The description only restates the filter axes generically ('keyword, CPV code, region and value') without adding syntax or interplay rules (e.g. how keywords and exclude combine). 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+resource: UK public sector tenders open for bids and contract awards, and names both upstream sources (Find a Tender and Contracts Finder). It also scopes the data returned for awards (winning suppliers with Companies House number, email, phone), so an agent knows exactly what it is getting.

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 usage context: mode selection between open bids and awards, and the filter axes (keyword, CPV, region, value). There are no competing sibling tools to route away from, so the absence of explicit exclusions costs little, but it never states when this tool is the wrong choice (e.g. non-UK procurement).

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