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

The description discloses key behavioral aspects beyond the annotations: it mentions that install/uninstall/subscribe/cancel require workspace owner/admin, that invoke runs one-off without installation, and that paid MCPs may return checkout links for billing. This provides substantial transparency about side effects and authorization, which is not present in 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 excessively long and repetitive. It redundantly explains the flow for both MCPs and prompts, and repeats the 'use install only...' guidance multiple times. While it is front-loaded with purpose, the verbosity and duplicated content detract from clarity and structure.

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?

The description covers the overall workflow, including search, describe, invoke, install, and prompt operations, along with billing and permission notes. However, it does not elaborate on the JSON formats for 'arguments' or 'conversation', nor does it detail fields like 'cancel_reason' or 'prompt_vars'. Given the tool's complexity (23 parameters, 0% schema coverage), this leaves gaps that could confuse an agent.

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?

The description explains the main 'action' parameter and its enumerated values, and gives high-level context for parameters like 'immediate', 'tier_slug', and prompt-related fields. However, many parameters (e.g., 'arguments', 'conversation', 'cancel_reason') are not individually explained, and the schema has no descriptions, so the coverage of parameter semantics is partial.

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 states the tool's purpose: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It also clarifies the core flow (search → describe → invoke) and distinguishes between MCP and prompt library functions, making it distinct from sibling tools like authenticate or connect.

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, e.g., '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 describe vs. invoke and mentions that writes require owner/admin. This gives clear when-to-use direction, though it does not explicitly compare against sibling tools like authenticate or connect.

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