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

Beyond the sparse annotations (readOnlyHint:false, openWorldHint:true), the description discloses critical behaviors: 'invoke works even when the MCP is NOT installed', one-off execution, return of connect/checkout links, permission requirements ('Writes require workspace owner/admin'), and the prompt library distinction. This adds substantial non-obvious 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. While information-rich and somewhat front-loaded with the core value proposition, it would benefit from bullets or sections given its length. The lack of formatting undermines scannability for an agent.

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 (23 params, multiple action types, billing/auth edge cases, prompt library), the description covers every major flow and provides comprehensive operational guidance, including permissions, auth, billing, and fallback behaviors (connect/checkout links). No missing critical context is apparent.

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 and 23 parameters, the description carries the burden. It explains the semantics of key actions (search, describe, invoke, install, list_tools, subscribe/cancel, report_bug, request_mcp, search_prompts, get_prompt, publish_prompt) and mentions auth/billing parameters indirectly. However, it does not systematically tie every parameter (e.g., limit, query, tier_slug, conversation) to its purpose, leaving some guesswork.

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 a precise statement: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It further clarifies scope with concrete examples of capability requests and the core flow (search → describe → invoke), clearly distinguishing it as the marketplace hub among siblings.

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?

Explicit when-to-use guidance is abundant: 'Use install only to make an MCP PERMANENT', 'prefer invoke for a single/occasional use', and 'list_tools lists what is callable right now.' It also explains when report_bug, request_mcp, and subscribe/cancel apply, effectively covering alternatives and exclusions.

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