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

With no annotations, the description carries the burden and does well: 'Public, no key, read-only' discloses auth and safety profile, and 'live prices' signals data freshness. Pagination behavior and result shape are not described, leaving a modest gap.

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 sentence, front-loaded with the purpose and the consuming sibling before enumerating sources. Every clause carries information, though the semicolon chain is packed enough that it reads as a list rather than prose.

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 five-param, no-output-schema discovery tool, the description covers sources, auth, read-only posture, and filtering. Missing pagination semantics and any hint of response fields keeps it from fully complete.

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 compensate, and it does so for the highest-risk parameter by explaining all four source enum values and noting category/search filtering. The page and limit parameters go unmentioned, but they are conventional defaults.

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?

Specific verb and resource ('Discover L402 APIs') plus an explicit tie to the consuming sibling pay_l402_api, so the agent knows this is discovery, not payment. The four source variants further pin down what the tool returns, distinguishing it from gateway_list/gateway_catalog.

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 tells the agent how to steer the tool (first_party for live prices, registry for community directory, discovered for observed payments, gateway for seller endpoints), which is clear usage context. It stops short of explicit when-not-to-use guidance versus siblings like gateway_list or gateway_catalog.

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