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

Beyond the annotations, the description discloses key runtime behaviors: invoke runs the MCP one-off without installing it and 'without bloating the tool list', returns a connect link when credentials are needed, and returns a checkout/top-up link if paid and wallet is empty. It also reveals that writes require owner/admin. Nothing contradicts the annotations (readOnlyHint=false, destructiveHint=false).

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 the tool is genuinely complex with 14 actions and 23 parameters. It is well-organized with headings like 'Core flow', 'KEY', and 'It also carries...', and front-loads the primary search→describe→invoke usage. A few sentences are dense, but every sentence adds meaningful guidance.

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 and absence of an output schema, the description is exceptionally complete. It covers the full lifecycle (search, describe, invoke, permanent install), permission requirements, handling of missing credentials or wallet, and the entire prompt library subsystem. It addresses all major capabilities and exceptional flows.

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 well by explaining the meaning of core parameters through the workflow (action, mcp_id, tool_id, arguments, prompt_slug, prompt_vars, etc.). However, it leaves several parameters underdescribed, such as limit, immediate, tier_slug, cancel_reason, conversation, prompt_body, and prompt_targets, so some semantics are still left to inference.

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 opens with 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them', clearly stating the verb+resource. It goes on to define the core search→describe→invoke flow and differentiates itself from sibling tools by explaining its coverage of MCP discovery, execution, installation, billing, and 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 explicitly instructs when to use which action: 'prefer invoke for a single/occasional use', 'Use install only to make an MCP PERMANENT', and contrasts invoke with list_tools ('list_tools lists what is callable right now'). It also provides the search→describe→invoke sequence and notes that writes require workspace owner/admin, plus covers the prompt library actions.

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