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

Despite the sparse annotations (only readOnlyHint=false, openWorldHint=true), the description discloses key behavioral traits: invoke runs one-off without installing, may return connect/checkout links, writes require owner/admin, and search/describe flag installed status. It adds value beyond annotations by explaining the one-off execution semantics and credential/billing contingencies. No conflict with 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 a single dense paragraph with many sentences and no bullets or numbering. It front-loads the name but then goes into a long string of actions and caveats, making it hard to scan. While the content is substantive, the structure is not optimized for quick comprehension; it would benefit from breaking into sections (Marketplace actions, Prompt Library, Authorization, etc.).

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 complexity (23 parameters, 14 actions, no output schema), the description does not fully explain all actions and their returns. It covers core actions but omits details for subscribe/cancel (tier_slug, cancel_reason), report_bug (report_context), request_mcp (request_name, request_details), and prompt library specifics (prompt_vars, prompt_targets). Without an output schema, the return values are not described for most actions, leaving the agent to guess.

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 coverage is 0%, so the description must compensate for parameter meaning. It explains the action enum (search, describe, invoke, etc.) and some flow-related parameters implicitly (e.g., 'action=search' implies query is the intent). However, it does not explicitly map many parameters like mcp_id, tool_id, arguments, limit, message, or the prompt_* fields to their functions. It provides directional knowledge but lacks systematic coverage, leaving a gap for a tool with 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 clearly states what the tool does: it is the mcp.ai marketplace catalog and execution engine. It covers a wide range of actions (search, describe, invoke, install, prompt library, etc.) and explicitly distinguishes itself from sibling tools like authenticate or connect. The verb 'marketplace' is defined as the in-platform catalog and method to run MCPs, making the purpose unmistakable.

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 when-to-use guidance, including the core flow: search -> describe -> invoke, and contrasts invoke vs install ('prefer invoke for a single/occasional use') with clear rationale. It also gives exclusion criteria (e.g., 'Use install only to make an MCP PERMANENT') and mentions authorization requirements for writes (owner/admin). This is exactly the kind of alternative-selection guidance expected.

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