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

The description adds substantial behavioral context beyond annotations: invoke works one-off even when the MCP is not installed, returns connect links for missing credentials and checkout links for empty wallet payment, writes require workspace owner/admin, and prompt links open without login. It also clarifies the side effects of install vs. invoke. This fully discloses safety, permissions, and state-changing implications.

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 dense single paragraph (~250 words) that packs in a lot of useful information without filler. Each sentence adds value, but the wall-of-text structure makes it harder to scan; bullet points or short sections would improve readability. Given the tool's complexity, the length is justified, but it's not maximally concise.

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 tool with 14 actions, 23 parameters, and no output schema, the description covers the major flows well: search/describe/invoke/install, prompt library operations, auth requirements, and payment/connect handling. However, it omits details on many parameters and doesn't describe return formats beyond saying 'describe returns one MCP's full profile'. The description is strong but not fully complete for an agent to invoke every action correctly without additional inference.

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 description mentions the main action enum values and high-level parameter roles (e.g., action=search, describe, invoke, install; tool_id, mcp_id, arguments), but with 23 parameters and 0% schema coverage, it leaves many parameter meanings to inference. For instance, 'immediate', 'tier_slug', 'report_context', 'conversation', and 'prompt_targets' are never explained. The description adds some value but does not compensate for the schema's lack of descriptions.

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 opens with 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them', clearly identifying both cataloging and execution as the core purpose. It distinguishes this tool from siblings by covering a unique combination of discovery, evaluation, invocation, installation, and prompt-library functions. Even with this breadth, it remains actionable and specific.

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 explicitly maps the core flow (search → describe → invoke) and provides when-to-use guidance for key alternatives, such as 'prefer invoke for a single/occasional use' and 'Use install only to make an MCP PERMANENT'. It also distinguishes between the marketplace's search/describe for discovery vs. list_tools for currently callable tools, and explains prompt-library search vs. publish. This is model guidance for choosing among the tool's many actions.

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