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

Adds substantial behavioral context beyond the annotations: a hard rate limit of 3 free calls/day shared across all tools, a $0.012 USDC price, and the exact in-band payment mechanism via params._meta["x402/payment"]. That payment detail is critical and appears nowhere in the annotations or schema. It's consistent with readOnlyHint=true and openWorldHint=true.

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?

Three tight sentences with no filler; the pricing/rate-limit preamble is front-loaded so cost is known before committing. Slight awkwardness in leading with billing before stating what the tool does, but nothing is wasted.

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?

Because an output schema exists, return values needn't be explained, and the description covers cost, quota, payment flow, and scope plus a docs link. The only meaningful gap is sibling routing guidance for an agent choosing among the many discovery tools.

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?

The single 'q' parameter is fully documented in the schema with examples, so baseline is 3 per the coverage rule. The description adds only the unschema'd payment meta-parameter, which is behavioral rather than semantic detail about the search input itself.

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 set: 'Discover AI-agent tooling in one call: matching MCP servers, x402 pay-per-call services and agent tools for any query.' The tri-resource scope distinguishes it from single-resource siblings like mcp_servers or x402_services, though the sibling names are never mentioned.

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?

'Built for agents that need to find and chain new capabilities at runtime' implies the use case but gives no explicit when-to-use/when-not, and never names the obvious alternatives (mcp_servers, x402_services, agent_tools) that this pack aggregates. An agent has to infer that this is the broad-search option versus the targeted siblings.

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