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

The description discloses critical behaviors beyond annotations: invoke works even when the MCP is not installed, returns a connect link for credentials or checkout link for payment, and writes require workspace owner/admin. These nuances are not visible in annotations and are essential for correct usage.

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 logically organized with labeled flows ('Core flow:', 'KEY:', 'Search/describe', 'Writes', 'It also carries the PROMPT LIBRARY'). Every sentence contributes meaningful information, though a bit more formatting or bullet points could improve scanability. The density is appropriate for the tool's complexity.

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?

Covers all major functional areas: discovery, description, invocation, installation, billing, feedback, and prompt library. It explains what happens when credentials are missing or wallet is empty, and mentions installed_in_toolkit vs installed_in_workspace flags. Given the tool's complexity and absence of an output schema, this is nearly complete, though per-action return formats could be more detailed.

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 23 parameters and 0% schema description coverage, the description takes on the burden and does so well for core parameters: action, mcp_id, tool_id, arguments, prompt_slug, prompt_vars. It explains the meaning of each action enum value and key inputs, though it does not exhaustively cover all parameters like limit, immediate, or cancel_reason. Still, it adds substantial meaning beyond the 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 opens with a clear, specific statement: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It goes on to explain the core flow (search → describe → invoke) and distinguishes itself from sibling tools like toolkit_info or authenticate by framing itself as the central catalog and execution layer.

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?

Provides explicit when-to-use guidance: 'Use install only to make an MCP PERMANENT... prefer invoke for a single/occasional use.' It also clarifies list_tools for currently callable tools, and differentiates the prompt library workflow (search_prompts/get_prompt/publish_prompt). This gives clear direction on action selection and alternatives within the tool.

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