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

With annotations only indicating readOnly=false and openWorld=true, the description carries valuable extra context: invoke runs uninstalled MCPs one-off without bloating the tool list, missing credentials produce a connect link, unpaid paid tools produce a checkout/top-up link, and all writes require workspace owner/admin. This goes well beyond the 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 information-dense and front-loaded with the core marketplace positioning, but it is a single long paragraph with many semicolons and em-dashes. Every sentence adds value, but the structure could be improved with bullets or separation of marketplace vs prompt-library concerns.

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, no output schema, and minimal annotation detail, the description covers the vast majority of behavior: discovery, execution, install vs invoke, auth requirements, billing edge cases, installed-status flags, prompt library operations, and admin write permissions. Minor gaps like the 'resume' action are acceptable given the breadth.

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?

Schema coverage is 0% with 23 parameters, so the description must compensate — and it does. It maps action values to their purpose, explains how tool_id is chosen from describe, covers prompt-related fields, and clarifies the arguments flow for invoke. While not every parameter is mentioned, the key decision-driving parameters are clearly explained.

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 explicitly states the tool is the official mcp.ai marketplace, the in-platform catalog of every MCP/tool, and the way to run them. It defines the core flow (search → describe → invoke) and clearly distinguishes itself from siblings by covering both discovery and execution, plus the prompt library.

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 extensive when-to-use guidance: prefer invoke for one-off use, install only for permanent toolkit membership, list_tools for currently callable tools, subscribe/cancel for billing, report_bug for feedback, request_mcp for new MCPs, and search_prompts/get_prompt/publish_prompt for prompt text. It also explains the retry flow after connect/checkout links.

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