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

Beyond the annotations, the description discloses crucial behaviors: invoke works even when MCP is not installed, returns a connect link when credentials are needed, returns a checkout link when wallet is empty, and writes require workspace owner/admin. It also explains installed_in_toolkit vs installed_in_workspace flags. No contradiction with annotations.

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 long but information-dense. Every sentence adds value, covering core flows, edge cases, permissions, and the prompt library. It is front-loaded with the central purpose and then expands logically, though it could benefit from clearer section breaks between the MCP marketplace and prompt library.

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 23 parameters, no output schema, and a wide action set, the description is remarkably complete. It explains discovery, invocation, installation, billing, permissions, credential handling, and the prompt library. It covers edge cases like connect links and checkout links, and describes the difference between one-off and permanent installation.

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 carries the burden of explaining parameters. It covers the key ones: action, mcp_id, tool_id, arguments, prompt_body, prompt_slug, etc., by associating them with actions. It does not explain every parameter (e.g., tier_slug, immediate, cancel_reason) but adds substantial meaning beyond the raw schema.

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 states what the tool is: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It uses a specific verb (catalog + run) and identifies the resource (MCPs/tools). It distinguishes itself from siblings by covering the full discovery-to-invocation flow.

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 gives explicit when-to-use guidance: 'prefer invoke for a single/occasional use' vs 'Use install only to make an MCP PERMANENT'. It also explains the core flow (search → describe → invoke), when to use subscribe/cancel, report_bug, and request_mcp, and contrasts with list_tools ('lists what is callable right now').

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