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

Annotations already mark the tool as read-only, idempotent, and non-destructive, but the description adds substantial context beyond them: it discloses cost per call, the maximum of 10 matches, the exact return fields, that contact names/emails/phones are excluded, that it is not the official notice, and that notices can change or close after the data date. This is exactly the kind of behavioral detail an agent needs to call the tool responsibly.

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?

The description is front-loaded with the cost and action, followed by return details and caveats. Every sentence carries useful information, though the first sentence is long and dense. It could be slightly more structured, but there is no filler or repetition.

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 no output schema, the description fully explains the return shape: up to 10 matches, the fields included, total matched, data date, and attribution. It also covers cost, exclusions, and data freshness caveats. Combined with the annotations, an agent has everything needed to call and interpret the tool correctly.

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 schema itself documents all five parameters thoroughly. The description adds one important semantic not present in the schema: 'give at least one' filter is required even though all parameters are technically optional. It also enumerates the filter types, reinforcing their purpose. The baseline is 3 when schema coverage is high, but the added constraint lifts this to 4.

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?

The description opens with a specific verb and resource: 'search the Government of Canada's published CanadaBuys tender notices'. It names the exact filters (keyword, procurement category, region, closing date range), so an agent can immediately understand what the tool does. Sibling tools are unrelated, but the purpose is still sharply distinct.

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 gives a clear usage constraint: 'give at least one' of the filter parameters. It also notes the tool is 'PAID, per call' and that 'You are not charged when nothing matches', which helps an agent decide when to invoke it. There are no explicit exclusions or named alternatives, but the sibling set contains no overlapping tools, so the context is sufficient.

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