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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds genuinely new context: data provenance (OCDS awarded tenders), per-match period/sources/computed_at fields, and the notable behavior that an empty matches list is accompanied by a note explaining why. The auth requirement (identified agent key with self-service URL) is also disclosed, which annotations do not capture.

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?

A single dense paragraph that front-loads the purpose, then metrics, then input routing, then provenance and auth. Every clause carries information, though the runway of parenthetical metric names makes it slightly hard to scan.

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 an output schema present, return values need not be re-explained, and the description still covers provenance, empty-result handling, and access requirements. The gaps are the undocumented limit and preferred_language parameters and the lack of a precedence rule among the identifier inputs.

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 0%, so the description must carry the load; it explains where tender_id comes from and that buyer_name or buyer_id are alternatives, but says nothing about limit or preferred_language, nor whether the three identifiers are mutually exclusive or which takes precedence.

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 uses a concrete verb-plus-resource framing ('learn how a buyer behaves before bidding') and enumerates the specific metrics returned (median_bidders, single_bidder_share, median_award_to_estimate), so an agent can distinguish this from supplier_history or assess_fit without opening the 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?

It states the timing of use ('before bidding') and routes the agent by naming search_tenders as the source of tender_id, plus the alternative buyer_name/buyer_id lookups. It does not explicitly exclude or contrast with the sibling supplier_history tool, keeping it short of a 5.

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