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

Beyond the annotations (readOnlyHint=false, etc.), the description reveals critical behaviors: invoke runs one-off without installing the MCP, returns a connect link when credentials are needed, returns a checkout link when the wallet is empty, and that writes require workspace owner/admin. It also explains that install/subscribe/cancel modify billing and toolkit state, which is rich context the annotations do not provide.

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 dense and front-loaded with the core flow and key behavior. It efficiently covers 14 actions and two major domains (MCPs and prompt library) without wasting words, though a bulleted structure could improve scannability. Every sentence adds value, so it earns a high score.

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, no output schema, limited annotations), the description is exceptionally complete. It explains end-to-end flows, authentication/billing edge cases, permission requirements, and even the prompt library's shareable-link behavior. It gives agents enough context to select actions and handle typical scenarios correctly.

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?

Although the schema has 0% description coverage, the description compensates by explaining the core action parameter and key parameters like mcp_id, tool_id, arguments, and immediate within the context of the search/describe/invoke flow. It does not detail every parameter (e.g., cancel_reason, prompt_vars), but the action-oriented explanation makes the most important semantics clear.

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 this is the official mcp.ai marketplace catalog and execution engine, with specific verbs like 'search', 'describe', 'invoke', and 'install'. It distinguishes itself from siblings by covering discovery, one-off execution, permanent installation, billing, and prompt library actions, leaving no ambiguity about its role relative to the other tools.

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 explains when to use invoke vs install, noting 'prefer invoke for a single/occasional use' and 'Use install only to make an MCP PERMANENT'. It also provides the core flow (search → describe → invoke) and mentions alternative actions like list_tools for currently callable tools, and request_mcp for building new ones, giving clear decision guidance.

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