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

Despite annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false) not providing much depth, the description discloses critical behavioral traits: invoke runs uninstalled MCPs one-off without bloating the tool list, returns connect links for credentials or checkout links for payment, writes require workspace owner/admin, and search/describe flag installed status. This richly supplements the 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 well-structured, starting with an overarching definition, then a 'Core flow' sequence, a 'KEY' emphasis on invoke, and then distinct usage guidance for install, list_tools, subscribe/cancel, and the prompt library. Each sentence adds value, but the text is dense and runs on in places; a slightly more scannable structure would improve it.

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 high complexity (14 actions, 23 parameters, no output schema), the description is exceptionally complete. It covers the main workflow, edge cases for auth/payment, permission requirements, the distinction between installed and one-off usage, and the additional prompt library subsystem. It even explains what describe returns (profile with tools, ids, params, pricing, auth) and how search flags installed status.

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 description coverage is 0%, so the description carries the full semantic burden. It explains the meaning of key parameters: action (enumerated flow), mcp_id, tool_id, arguments, prompt_slug, prompt_vars, etc. However, some parameters (limit, immediate, tier_slug, cancel_reason) are not explicitly described, leaving gaps. The compensation is strong for the core use cases but not exhaustive across all 23 params.

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' with a specific scope: cataloging and running MCPs/tools. It distinguishes itself from siblings by detailing a core flow (search → describe → invoke) and naming distinct actions like list_tools and prompt management. This is a specific verb+resource with strong differentiation.

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 guidance is abundant: 'prefer invoke for a single/occasional use' vs. 'Use install only to make an MCP PERMANENT'. It clarifies when each action is appropriate (e.g., 'list_tools lists what is callable right now', 'report_bug sends feedback', 'request_mcp asks us to build a NEW MCP when nothing fits'). This goes beyond general context and offers clear when-to-use versus alternatives.

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