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

Beyond the annotations (readOnlyHint: false, openWorldHint: true, etc.), the description adds rich behavioral context: invoke works even when the MCP is not installed, returns connect/checkout links for credential/payment issues, and notes that write actions require workspace owner/admin. It also reveals that invoke performs a behind-the-scenes one-off install. No contradictions with annotations are present.

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 (multiple sentences) but logically structured: it starts with the core purpose and flow, then covers important behaviors, usage guidance, and the prompt library. While some sentences could be tightened, each adds meaningful information for a tool with many actions and edge cases.

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 large parameter count (23) and no output schema, the description covers the essential workflow, authentication requirements, and prompt library thoroughly. It explains when to use which action and what to expect in terms of links and permissions. However, it omits some details like the 'resume' action and the 'immediate' parameter, preventing a perfect score.

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 schema has 0% description coverage, but the description compensates by explaining the meaning of the 'action' enum values and the core workflow (search, describe, invoke, install, prompt functions). It gives context for parameters like mcp_id, tool_id, arguments, and prompt_vars. However, it does not explain many parameters (limit, immediate, tier_slug, cancel_reason, etc.), leaving some gaps in semantic understanding.

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 that the tool is 'the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It identifies a specific resource and function, while distinguishing itself from sibling tools by being the central hub for discovery and execution. The explicit core flow (search → describe → invoke) reinforces its unique role.

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 provides explicit when-to-use guidance: 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It also differentiates list_tools for what is currently callable, request_mcp for building new MCPs, and the prompt library functions for prompt text. This clearly directs the agent to the right action.

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