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

Annotations only state readOnlyHint=false and openWorldHint=true, but the description adds substantial behavioral detail: invoke runs tools one-off without installing or bloating the toolkit; if credentials are needed it "returns a connect link"; if paid and wallet empty it returns a checkout link and instructs the agent to retry after user action; writes require workspace owner/admin. This far exceeds the annotation baseline and clarifies side-effect and auth behavior.

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 well-structured, using labeled segments like "Core flow:" and "KEY:" to front-load critical behavior. There is minor redundancy (the point about not adding to the toolkit appears twice), but given the tool's 23 parameters and multiple sub-flows, every sentence earns its place and the structure aids scanning.

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?

The description covers the main marketplace flow, the prompt library subsystem, permission requirements, and payment/auth edge cases — impressive for a tool with no output schema or param descriptions. It omits the 'resume' action and doesn't detail return formats, but for the described use cases it provides enough context to invoke the tool effectively.

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 0% schema description coverage, the description compensates by explaining the main action parameter values (search, describe, install, invoke, etc.) and the roles of mcp_id, tool_id, prompt_slug, prompt_vars, and arguments within the flow. It does not document every one of the 23 parameters (e.g., limit, message, request_details are not explained), but the high-level semantic mapping of the core parameters is clear and useful.

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 establishes the tool as the mcp.ai marketplace: "the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them." It goes beyond a simple verb+resource by outlining the core flow (search → describe → invoke) and explicitly differentiating from sibling tools like authenticate and connect by describing the marketplace's meta-tool 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 gives 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 contrasts list_tools as "what is callable right now" and explains when each action (search, describe, invoke, install, subscribe, cancel, report_bug, request_mcp) is appropriate, providing clear decision paths over alternatives.

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