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

Annotations only cover the safe-read profile (readOnly, openWorld, idempotent). The description adds the non-obvious behavioral layer: paid per-call access at $0.10 USDC on Base via x402, and the crucial flow that it returns payment requirements rather than data unless payment_signature is supplied. That payment/auth behavior is nowhere in the structured fields.

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?

Five short, front-loaded sentences: what it does, when to use it, cost/payment behavior, then a sample reference. No filler, and the routing information comes before the pricing mechanics.

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 9-parameter, no-required-args read tool with full schema coverage and no output schema, the definition covers purpose, trigger, and payment mechanics. It does not describe the returned notice shape or result limits/ordering, but annotations and the sample path partly cover the gap.

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 description coverage is 100%, with rich per-parameter docs (CPV divisions, Brussels-time since window, ECB conversion for min_value, notice_type semantics), so the schema carries the burden and 3 is the baseline. The description only clarifies the conditional role of payment_signature, adding little beyond what the schema already says.

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 ('Get the new EU public tenders') plus the defining scope: notices matching a company's criteria since the last check. The incremental 'new since last check' framing cleanly separates it from siblings like search_tenders and search_tender_awards.

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?

Explicitly names the situation ('daily tender alert or bid-pipeline feed'), which tells an agent when this tool fits. It stops short of naming the alternative siblings (search_tenders / search_tender_awards) or stating when not to use it, so there is no exclusion guidance.

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