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

The description discloses critical behaviors beyond the annotations: invoke works on non-installed MCPs, returns connect/checkout links for auth/payment, and writes require owner/admin. It also explains installed_in_toolkit vs installed_in_workspace flags. The annotations (readOnlyHint: false, etc.) are consistent, and the description adds rich detail without contradiction.

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 lengthy but well-structured: it opens with the core purpose, then explains the flow, key behaviors, and separates the MCP and prompt-library components. It is dense without redundancy, though it could be tightened by splitting into bullet points for readability.

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 no output schema and high param count, the description covers the main actions and their return behaviors (e.g., describe returns a full profile, invoke returns links for auth/payment, list_tools lists callable tools). It does not describe outputs for every action (e.g., subscribe/cancel) but provides enough for the primary flows.

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 params and zero schema descriptions, the description carries the full burden. It explains how action determines which parameters matter (e.g., query for search, mcp_id for describe/install, tool_id and arguments for invoke, prompt_slug for get_prompt). However, not all parameters are explicitly mapped, and some defaults (like immediate, tier_slug) are left implicit.

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, covering both catalog discovery and tool execution, and explicitly enumerates its actions (search, describe, install, invoke, etc.). It distinguishes itself from siblings like authenticate or report_bug by its comprehensive scope as the central hub for MCPs and prompts.

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, outlining the core action flow (search → describe → invoke) and clearly stating when to use install vs invoke, when to use subscribe/cancel, and how to handle the prompt library. It also includes query examples like 'find an MCP that does X', giving concrete trigger scenarios.

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