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

Annotations only carry readOnlyHint=true, so the description carries most transparency burden; it excels at it. It discloses anonymity for non-authenticated callers, the exact withheld fields and withheld_reason, no currency conversion, computed_at meaning, and source attribution requirements. This is far beyond generic and does not contradict the read-only hint.

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 long but well-structured: a one-line summary, then a clearly marked when-to-use block, then response contents, then caveats. The front-loading respects agent scanning. A little redundancy ('what they plan' vs 'planned procurements') is negligible.

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 two-parameter read-only tool, the description is unusually complete: it explains parameter semantics, output fields, anonymity behavior, time semantics, currency handling, and geographic coverage. The presence of an output schema lowers the burden for return-value documentation, and this description still covers it. No critical operational detail 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 has no descriptions for either parameter (0% coverage), so the description must compensate and does: it defines buyer as 'the organisation name as published' and buyer_key as coming 'from a tender's buyer, or a previous answer.' It also clarifies that either is acceptable. This is the only real documentation the parameters get.

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 plain-language statement of what the tool returns—'What a buyer has awarded, what is ending, and what they plan'—and later names the concrete result object. It distinguishes itself from siblings by framing the use case as 'a specific buyer before a bid,' which is clearly different from generic tender search tools like find_tenders.

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 explicit triggering conditions ('USE THIS WHEN someone asks about a specific buyer before a bid') with three realistic example queries. It also tells the caller which parameters to supply and where to get them, but it does not name sibling tools or state when a different tool should be used instead.

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