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

The description goes well beyond the annotations by disclosing key behaviors: invoke runs tools even when not installed (one-off), returns connect or checkout links when credentials or payment are needed, and that writes require admin. It also explains the distinction between installed_in_toolkit vs installed_in_workspace and the prompt library's shareable links. No contradictions 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 lengthy (multiple paragraphs) but well-structured: first paragraph introduces the marketplace and core flow, second dives into the invoke behavior, third covers permissions, and fourth describes the prompt library. Information is front-loaded with the most critical details. While it could be tightened, every sentence adds value, so it earns a 4 rather than a lower score for wordiness.

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, 14 actions, multiple sub-systems), the description is remarkably complete. It covers the end-to-end flow, edge cases (non-installed MCPs, credential/payment links), permissions, and the separate prompt library. Without an output schema, it explains enough about returns (e.g., connect/checkout links) to guide the agent. It fully equips an agent to decide when and how to use the tool.

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 must compensate. It explains the action enum thoroughly (each action's purpose), and references key parameters like mcp_id, tool_id, arguments, and prompt_* in the flow explanations. Some parameters (e.g., limit, immediate, conversation) are not explicitly described, but the overall semantics for the primary use cases are covered. It doesn't fully enumerate every parameter but provides enough context to infer most.

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 identifies the tool as the official mcp.ai marketplace catalog and execution platform, with specific actions (search, describe, invoke, install, etc.). It distinguishes itself from siblings by being the central hub for discovering and running MCPs, and it mentions the prompt library as an additional capability, making its purpose unmistakable.

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 guidance on when to use each action: use invoke for one-off runs, install for permanent additions, search/describe for discovery, and prompt functions for prompt text. It also contrasts with alternatives (e.g., 'prefer invoke for a single/occasional use' versus install) and notes permission requirements (writes need workspace owner/admin), giving clear when-to-use and when-not-to-use context.

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