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

Annotations only provide readOnlyHint false, openWorldHint true, etc. The description adds key behavioral details beyond that: invoke works even when MCP is not installed and runs one-off without bloating the list; credential needs return a connect link; payment needs return a checkout/top-up link and then retry; install makes permanent. 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 long but dense with necessary information covering multiple actions, permissions, failure modes, and the prompt library. It is front-loaded with the core purpose and structured as a clear flow ('Core flow: action=search ... → describe ... → invoke'). Minor redundancy and the mixed-language term 'pontualmente' slightly mar conciseness.

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 complex tool with 23 optional parameters and no output schema, the description covers the full lifecycle: discovery, description, invocation, installation, billing, permissions, bug reporting, MCP requests, and the prompt library. It addresses auth and payment edge cases and distinguishes installed vs. permanent states, making it sufficient for correct tool selection and invocation.

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 has zero descriptions for 23 parameters. The description compensates by explaining the core parameters through the flow: 'action=search discovers MCPs by intent → describe returns one MCP's full profile (every tool with its id + params, pricing, auth) so you pick the right tool_id → invoke RUNS that tool.' It also covers prompt_vars, prompt_slug, etc. However, it does not explicitly map all 23 parameters (e.g., limit, immediate, tier_slug, cancel_reason).

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 explicitly identifies the tool as 'the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It enumerates concrete capabilities (search, describe, invoke, install, etc.) and clearly differentiates from sibling tools like authenticate/connect by focusing on catalog execution and prompt library features.

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?

It provides explicit when-to-use guidance: 'prefer invoke for a single/occasional use' vs. 'Use install only to make an MCP PERMANENT,' and distinguishes actions like 'subscribe/cancel handle per-MCP billing; report_bug sends feedback; request_mcp asks us to build a NEW MCP.' It also states permission requirements: 'Writes ... require workspace owner/admin.'

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