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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the bar is lower. The description still adds genuinely non-obvious operational context: pricing (0.005 USDC via x402 or 3 API credits) and a free tier of the first 5 paid calls per day. It does not mention result caps or pagination.

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?

Four tight sentences, front-loaded with the usage trigger, then scope, then the NL extension, then cost. Every sentence carries information an agent needs before calling.

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 correctly summarizes the return payload (English titles, buyer, deadline, value) and covers payment/auth before the call is made. Missing only edge detail: result limits, pagination, and accepted formats for the value/deadline filters.

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 50%, and the description names the domain meaning of five filters (country, CPV, keywords, deadline, minimum value). However it gives no format guidance for the undescribed parameters (deadline_within, min_value, limit) — e.g. whether deadline_within is days or a date — so it only partially compensates for the coverage gap.

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 and resource ('search open public contracts/tenders') plus the authoritative source (TED, plus TenderNed for NL) and the filterable facets. No sibling tool in the list does tender sourcing, so the distinction is immediate.

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?

Opens with an explicit trigger: 'Use when the user looks for public contracts to bid on.' It also carves out the NL below-threshold case that TED does not cover. It stops short of naming when NOT to use it or pointing to an alternative for non-EU procurement.

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