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

Beyond annotations, the description discloses that writes require workspace owner/admin, that invoke works even when the MCP is not installed, and that invoke runs the tool without adding it to the toolkit. It also explains the connect/checkout link behavior and the difference between permanent (install) and one-off (invoke) execution, adding significant 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 long but densely packed, using a logical flow: core marketplace functionality, key behavioral notes, installation vs invocation, permissions, and a separate prompt library section. Every sentence adds value and the structure makes the complexity manageable. It front-loads the main purpose and clearly separates concerns.

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 23 parameters, no output schema, and broad open-world functionality, this description covers the essential context: the core flow, when to install vs invoke, credential/payment handling, permission requirements, and the prompt library with its own sub-actions. It gives the agent enough to operate correctly in most scenarios, including edge cases.

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 compensates well by explaining the core parameters (action, mcp_id, tool_id, arguments) through the search→describe→invoke flow and prompt-related params via the prompt library section. However, some parameters (e.g., immediate, tier_slug, cancel_reason, conversation) are not explicitly described, though the overall framework helps infer their roles. It adds substantial meaning beyond the bare schema.

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 identifies the tool as the official mcp.ai marketplace, acting as both a catalog and execution platform. It lists concrete actions (search, describe, invoke, install, etc.) and explicitly distinguishes itself from siblings by covering capability requests and MCP execution, not just authentication or simple utilities.

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 gives explicit guidance: use 'invoke' for one-off execution, 'install' for permanent addition, and names alternatives for other tasks ('subscribe/cancel handle billing', 'report_bug sends feedback', 'request_mcp asks us to build a NEW MCP'). It also explains when invoke returns connect or checkout links, teaching the agent how to handle auth and payment flows.

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