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

The description reveals key behaviors beyond the openWorldHint/readOnlyHint annotations: invoke can run uninstalled MCPs one-off, returns auth/payment links instead of failing, and writes require admin role. It also discloses the non-mutating nature of search/describe and the mutating nature of install/uninstall/subscribe/cancel, enriching the agent's understanding of side effects.

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 a single dense paragraph but is logically structured: it opens with the core purpose, then the main flow, key one-off behavior, edge cases (auth/payment), permission requirements, and finally the prompt library. Every sentence contributes value, though the length and density may slightly reduce scannability. It earns a 4 rather than 5 because it could be broken into clearer sections or bullets.

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?

Given the tool's complexity (23 parameters, 14 actions) and no output schema, the description is remarkably complete: it covers the core search-discover-invoke flow, auth and payment link behavior, install vs invoke trade-offs, permissions, billing actions, and the separate prompt library. Missing but minor: specific return shapes for search/list_tools and the exact role of 'immediate' or 'tier_slug'. Still strong overall.

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?

With 0% schema description coverage, the description compensates by explaining the meaning of the action parameter (search, describe, invoke, install, etc.) and the interplay between mcp_id, tool_id, and arguments. It also clarifies prompt-related parameters (prompt_vars, prompt_slug) via the prompt library explanation. However, it does not exhaustively cover parameters like limit, immediate, tier_slug, or conversation, leaving some ambiguity for obscure fields.

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 clearly identifies the marketplace as 'the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It explains the core flow (search → describe → invoke) and distinguishes list_tools from the discovery functions, setting it apart from sibling tools like report_bug and toolkit_info.

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?

Explicit guidance is provided throughout: 'Use install only to make an MCP PERMANENT... prefer invoke for a single/occasional use,' and 'list_tools lists what is callable right now.' It also describes when invoke returns connect/checkout links and notes that writes require workspace owner/admin. This directly answers when to use this tool versus alternatives.

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