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

Beyond annotations (readOnlyHint=false, etc.), the description discloses critical behavioral details: invoke works even when the MCP is not installed, returns a connect link for missing credentials or a checkout/top-up link for empty wallet, writes require workspace owner/admin, and the one-off install behind invoke is mentioned. It also explains return behaviors like the shareable prompt link, which is not covered by annotations or output schema.

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 rich, and nearly every sentence conveys essential guidance. It is front-loaded with the core definition, then flows through the action lifecycle and ends with the prompt library. While it could benefit from bullet points, the density is justified by the tool's complexity (14 actions, 23 params). It is verbose but not wasteful.

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 no output schema, the description is remarkably complete: it explains the entire action flow, permission requirements, error/next-step behaviors (connect/checkout links), and the prompt library sub-feature. It covers edge cases like non-installed MCPs and wallet shortages, making it sufficient for an agent to select and invoke the tool correctly.

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 the burden and explains the most important ones: action values (search, describe, install, invoke, list_tools, prompt actions), tool_id, arguments, and prompt-related fields. However, it does not explicitly describe parameters like limit, immediate, tier_slug, cancel_reason, conversation, or prompt_targets. It adds substantial value for core usage but not exhaustive parameter coverage.

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 is 'the official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It specifies the core flow (search → describe → invoke) and distinguishes this tool from siblings by covering all marketplace actions, including the prompt library. It is far from a tautology and explicitly defines its resource and verbs.

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 says when to prefer invoke for single/occasional use vs install for permanent toolkit inclusion, and it contrasts list_tools with 'callable right now' vs search/describe flags. It also gives alternatives: request_mcp for new MCPs, report_bug for feedback, and separates prompt library actions from MCP actions. This is clear when-to-use and when-not-to-use guidance.

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