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

The description goes far beyond the minimal annotations (readOnlyHint=false, openWorldHint=true) by disclosing important behaviors: invoke works even when MCP is not installed, runs one-off without bloating the toolkit, returns connect/checkout links for auth/payment, and retries after user action. It also notes permission requirements for writes. 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 a dense but well-organized paragraph that front-loads the core purpose and flow, then systematically covers actions, edge cases (auth/payment), and the prompt library. It is lengthy, but given the tool's complexity (14 actions, 23 params), every sentence contributes value. A bulleted breakdown could improve scannability, but it's appropriately detailed.

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 of this complexity with no output schema and 23 optional parameters, the description is remarkably complete. It covers all major actions, explains invocation behavior (including auth and payment flows), differentiates install vs invoke, notes permission requirements, and details the prompt library. It leaves few ambiguities about how to use 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 adds crucial meaning to the parameters, especially action, query, mcp_id, tool_id, arguments, and prompt-related fields, by explaining them through the workflow (e.g., action=search, describe returns profile, invoke runs tool). However, not all 23 parameters are explicitly explained (e.g., immediate, conversation, prompt_targets), leaving some gaps for less common fields.

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, a platform for discovering, describing, and invoking MCP tools, plus a prompt library. It specifies the core flow (search → describe → invoke) and distinguishes itself from siblings, which are specific standalone tools (e.g., authenticate, show_version).

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 for each action: use search to find MCPs, describe for profiles, invoke for one-off runs, install for permanent toolkit additions, and it even says 'prefer invoke for single/occasional use' vs 'use install only to make an MCP PERMANENT'. It also covers the prompt library actions and mentions that writes require owner/admin.

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