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

The description reveals numerous non-obvious behaviors: 'invoke works even when the MCP is NOT installed — it runs the tool pontualmente... without adding the MCP to the toolkit,' and that invoke returns connect/checkout links under credential/billing gaps. It also states 'Writes ... require workspace owner/admin.' These go well beyond the annotations (readOnlyHint=false, etc.) without contradicting them.

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 heavy punctuation, mixing core flow, permissions, billing, and prompt library in one stream. While nearly every sentence adds value, the lack of structure (bullets, sections) makes it harder to parse than necessary for 14 actions. It is comprehensive but not concise.

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 zero required params and no output schema, the description covers the full decision tree: discover→describe→invoke/install, plus list_tools, subscribe/cancel, and prompt library operations. It covers auth requirements, billing exceptions, and installed-state reporting. Minor omissions like the default action='search' and the format of the `arguments` parameter don't undermine the overall completeness.

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 0% schema description coverage, the description compensates by explaining the central action parameter and the workflow around it (e.g., 'describe returns one MCP's full profile (every tool with its id + params, pricing, auth) so you pick the right tool_id → invoke RUNS that tool'). It also clarifies prompt-related actions. However, many parameters (limit, immediate, tier_slug, cancel_reason, etc.) are left to inference from names, so the compensation 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 identifies the tool as the official mcp.ai marketplace and runner: 'in-platform catalog of every MCP/tool, AND the way to run them.' It distinguishes itself from sibling tools like toolkit_info by enumerating its search/describe/invoke/install capabilities. The verb is specific (catalog + run) and the scope is defined.

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 flow guidance: 'action=search discovers MCPs by intent → describe returns one MCP's full profile... → invoke RUNS that tool.' It explicitly contrasts invoke vs install ('Use install only to make an MCP PERMANENT... prefer invoke for a single/occasional use'), and lists what each subscription/reporting/request action is for. This is textbook when-to-use guidance.

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