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

The description goes far beyond annotations (readOnlyHint=false, destructiveHint=false) by disclosing that invoke runs one-off without bloating the toolkit, may return connect or checkout links, and that writes require owner/admin. It also segments the prompt library as a separate concern, providing comprehensive behavioral context.

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 single dense paragraph but exceptionally information-dense, with a logical flow from core flow to key behaviors to requirements to prompt library. It could benefit from bullet points, but all content is purposeful and front-loaded with the most important differentiators.

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 23 parameters, no output schema, and 14 distinct actions, the description is remarkably complete: it explains the end-to-end flow, permission requirements, fallback mechanisms for auth and payment, and segues into the prompt library. It covers all major use cases and edge cases, leaving little ambiguity for an agent to misuse it.

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 carries full responsibility for explaining parameters. It mentions major ones (action, query, mcp_id, tool_id, arguments, prompt_*), but leaves many unexplained (e.g., immediate, tier_slug, conversation, request_details, cancel_reason). While the action enumeration and core parameters are covered, incomplete documentation of the rest leaves agents guessing on advanced parameters.

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, governing both discovery and execution of MCPs. It enumerates distinct actions (search, describe, invoke, install, etc.) and explains the core flow, distinguishing it from sibling tools like authenticate and connect. The verb 'marketplace' plus the detailed breakdown leaves no ambiguity about what the tool does.

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, such as preferring invoke for one-off usage and install for permanent additions, and clarifies that invoke works even without installation. It also handles edge cases like auth and wallet links, and references list_tools for current callable tools, giving clear decision criteria among alternatives.

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