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

The description reveals many non-obvious behaviors: 'invoke works even when the MCP is NOT installed — it runs the tool pontualmente (one-off), without adding the MCP to the toolkit and without bloating the tool list.' It also discloses auth and billing edge cases ('returns a connect link', 'checkout/top-up link... then you retry') and permission requirements ('require workspace owner/admin'). This far exceeds the annotations' basic hints.

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 massive single paragraph that packs in many details, flows, and edge cases. Every sentence adds value, but the lack of bullet points or section breaks makes it harder to parse. It is front-loaded with the core purpose, though the sheer length hurts 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 multi-action tool with no output schema, the description is remarkably complete. It explains the main catalog flow, the install-vs-invoke distinction, authentication and payment fallback behaviors, the prompt library, and permission requirements. It even covers the shareable link behavior for published prompts.

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 coverage, the description must compensate for parameter meanings. It explains the central `action` enum and critical parameters like `tool_id` and `arguments` via the flow description ('describe returns one MCP's full profile... so you pick the right tool_id → invoke RUNS that tool'). However, several parameters (`tier_slug`, `immediate`, `cancel_reason`) are left unexplained, so it doesn't fully cover all 23 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 opens with a clear definition: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It then details the core flow (search → describe → invoke) and distinguishes itself from sibling tools by being the platform-wide catalog and runner.

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 usage guidance: 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It also explains when to use each action: 'subscribe/cancel handle per-MCP billing; report_bug sends feedback; request_mcp asks us to build a NEW MCP when nothing fits.' This goes beyond simple context to give clear when-to/when-not-to direction.

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