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

Annotations are minimal (readOnlyHint=false, openWorldHint=true, etc.), so the description carries the full burden. It discloses key behaviors: invoke runs tools even when not installed, returns connect/checkout links for auth/payment, and the one-off install behind invoke. Also clarifies write permissions. No contradictions found.

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 information-dense. It starts with the core purpose and immediately describes the flow, then covers key behaviors and permissions. Every sentence adds value, though some repetition (e.g., 'KEY: invoke works even when the MCP is NOT installed') could be tightened. The structure is logical: core flow, invoke specifics, install distinction, list_tools, subscription, and prompt library.

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 highly complex multi-action tool with 23 parameters and no output schema, the description is remarkably complete. It explains the primary user journeys, edge cases (auth/payment), permission model, and even the prompt library subsystem. No output schema exists, but the description describes expected outcomes (e.g., invoke returns links, describe returns profile). This is sufficient for an agent 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?

Schema coverage is 0%, but the description adds meaning to the critical parameters, especially 'action' by explaining each action's role (search, describe, invoke, install, etc.). It also implies the meaning of mcp_id, tool_id, and arguments through the flow description. However, it does not explain parameters like limit, query, cancel_reason, or prompt_* fields in detail, leaving some gaps.

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 states the tool's purpose: 'the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It distinguishes from siblings by explicitly naming list_tools as a separate tool and describing the unique invoke capability. The core flow (search→describe→invoke) is clearly articulated.

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?

Extensive usage guidance: explains when to use invoke vs install ('prefer invoke for a single/occasional use'), states permission requirements ('Writes require workspace owner/admin'), and covers edge cases like credential/login and payment links with retry instructions. Also mentions how search/describe flags distinguish installed states.

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