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

The description goes well beyond the annotations by disclosing side effects: 'Writes (install/uninstall/subscribe/cancel and the one-off install behind invoke) require workspace owner/admin.' It also explains the non-persistence of invoke, the conditions for returning links, and the behavior of the prompt library. No contradictions with annotations (readOnlyHint=false, openWorldHint=true) are present; the description actually reinforces that this tool can mutate state and make external calls.

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?

While every sentence adds value, the description is a dense wall of text in a single paragraph. It front-loads the purpose well but then crams numerous actions, edge cases, and prompts into a lengthy run-on style. Breaking it into bullet points or separate paragraphs for marketplace actions, install/invoke flow, and prompt library would improve scannability. It is appropriately sized for the complexity but lacks structural organization.

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 optional parameters and no output schema, the description is remarkably complete. It covers not only the primary flows but also edge cases (credential/login, wallet top-up, one-off invoke vs permanent install), permissions, and the prompt library. It even specifies behavior for missing prerequisites and how to handle them. No significant gaps were identified for the intended use 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% parameter descriptions in the schema, the description must carry the weight, and it does for core parameters: it explains the 'action' enum (search/describe/invoke/install/etc.) and implicitly defines 'mcp_id', 'tool_id', and 'arguments' through the narrative ('invoke RUNS that tool' with 'every tool with its id + params'). However, many parameters (e.g., 'limit', 'conversation', 'tier_slug', 'cancel_reason') receive no explanation, leaving room for ambiguity. Nonetheless, the most critical parameters are well covered, which is impressive given the tool's breadth.

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 opens with a clear, specific verb-plus-resource statement: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It unambiguously identifies the tool as the marketplace for discovering and executing MCPs, and it differentiates this tool from siblings by outlining its core flow (search/describe/invoke) and distinguishing it from other capabilities (prompt library). This satisfies the highest level of purpose clarity.

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 for different action modes: 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It also covers conditional paths like missing credentials ('invoke returns a connect link') and empty wallets ('invoke returns a checkout/top-up link'). However, it does not explicitly contrast with the sibling tools (e.g., 'use authenticate for login'), so it loses a point for not naming alternatives.

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