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

The description goes far beyond the annotations (readOnlyHint=false, openWorldHint=true, etc.). It discloses that invoke runs tools one-off even when the MCP is not installed, does not bloat the tool list, and returns connect/checkout links for auth/payment before retrying. It also details permission requirements for writes and explains the prompt library behaviors. No contradiction 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 dense and long, consisting of several sentences with many embedded clauses. It is front-loaded with the core purpose and flow, but the extensive behavioral detail is packed into a single wall of text rather than structured bullets. While most content is valuable, it could have been more concise and easier to scan, so it earns a 3.

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 high complexity (14 actions, 23 parameters, no output schema), the description covers a comprehensive set of contexts: the core search→describe→invoke flow, edge cases (not installed, missing credentials/wallet), permission requirements, install vs invoke trade-offs, and the separate prompt library. It addresses retry behavior and alternative tools sufficiently for an agent to act correctly.

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?

Although the schema has 23 parameters with 0% description coverage, the tool description explains the key parameter 'action' exhaustively by walking through each enum value (search, describe, install, uninstall, invoke, etc.). It also gives meaning to mcp_id, tool_id, arguments, and prompt-related parameters through the described flows. However, not every parameter is explicitly covered, and some defaults ('limit', 'query', 'immediate') are only implied, not defined.

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 uses specific verbs (catalog, run, discover) and a clear resource (MCPs/tools), and distinguishes itself from siblings like authenticate and connect by positioning itself as the central marketplace and execution platform.

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: 'prefer invoke for a single/occasional use', 'Use install only to make an MCP PERMANENT', 'list_tools lists what is callable right now', and explains retry flows for auth and payment links. It also specifies permission requirements ('Writes ... require workspace owner/admin'). This is strong when-to-use and alternative-guidance.

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