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

Annotations already declare readOnlyHint and openWorldHint, but the description adds concrete behavioral detail: it 'checks each result live without paying', explains ranking by live price quote and distinct paying wallets, and warns that 'nobody pays for placement'. It also discloses that descriptions are the sellers' own words, adding context beyond structured annotations.

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 compact and front-loaded: it opens with the core action ('Searches ...'), then adds behavioral and ranking details. Every sentence contributes distinct information with no redundancy or filler.

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 2-parameter, read-only search tool, the description covers discovery purpose, live-check behavior, ranking, and the caveat about seller-written descriptions. It does not detail the result output structure, but no output schema exists and the description gives enough to infer what results contain. Minor gaps like potential latency are acceptable.

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% and both parameters have descriptions. The description adds value by giving example query values ('product price lookup', 'send sms', 'web page screenshot'), which clarifies the expected format of the query parameter beyond the schema's generic 'What you need done, in plain words.'

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 states a specific verb-resource pair: 'Searches Coinbase's public x402 discovery index for services that do a task' and gives concrete examples. The title also clarifies its role. It distinguishes itself from siblings like check_service by searching an index rather than checking a specific service.

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 implies usage: use this to find a service for a task without paying, and notes that it live-checks results. However, it does not explicitly name alternatives or exclusion conditions, nor does it say when to prefer this over siblings like check_service or get_service_info.

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