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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=true. The description adds real context beyond them: it is free, requires no key, optionally accepts an auth header that is used 'for this read only, never stored', and the output is draft listings with delivery wiring rather than a published listing — consistent with the readOnly annotation.

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 core action is front-loaded, but the middle section ('Buyers here pay by card or Stripe Link, no wallet needed: assistants like Meta Muse can buy from you') is marketplace marketing that does not help an agent decide or call the tool. Trimming that would make the remainder tight.

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 usefully enumerates what comes back (title, description, suggested price, delivery wiring to the service) and notes the optional auth path and its storage behavior. That covers the main gaps for a two-parameter, open-world import tool, though it omits error/partial-import behavior.

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% and the nested auth object is fully documented in the schema, including the header enum and format guidance. The description only restates 'give its URL' and does not add format or edge-case detail beyond the schema, so the baseline of 3 applies.

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 and resource: give a URL of an MCP server, OpenAPI document, or x402 endpoint and get ready-to-post listings back, including the fields returned (title, description, suggested price, delivery). It does not name any sibling (e.g. create_listing) to differentiate this import path from manual listing creation, which keeps it below a 5.

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?

Usage is implied by the framing 'Seller: already run an MCP server...? Give its URL' — an agent can infer this applies when the seller already has a machine-readable service endpoint. There is no explicit statement of when NOT to use it, nor a pointer to create_listing for sellers without such an endpoint, so guidance is only implied.

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