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

Beyond the annotations (readOnly=false, openWorld=true, idempotent=false, destructive=false), the description reveals critical behaviors: invoke runs uninstalled tools without bloating the toolkit, returns connect/checkout links for auth/payment issues (then retry), one-off install require owner/admin, and prompt links open without login. These are non-obvious, actionable traits disclosed fully, with no contradiction to 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?

Every sentence is information-dense and earns its place, but the entire description is one giant paragraph without line breaks or sectioning, making it harder to scan. The front-loaded purpose statement helps, but the structure could be improved with bullet points or separate blocks for the marketplace flow, prompt library, and permissions.

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 is remarkably complete for a tool with 14 actions and no output schema. It covers all actions, the core user flow, auth and payment edge cases, permission requirements, installed-state flags, and the prompt library's shareable-link behavior. No aspect of the tool's operation is left unexplained, making it nearly self-sufficient for 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?

With 0% schema description coverage, the description carries the whole burden. It explains the meaning of key parameters: action's 14 enum values are all described, tool_id/arguments are contextualized in the invoke flow, mcp_id in describe/install, and prompt_* params in the prompt library. However, several params like limit, immediate, conversation, report_context, request_details, and prompt_targets are never explicitly mentioned, so the compensation is strong but incomplete.

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 opening sentence clearly defines the tool: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It goes on to explain the core search → describe → invoke flow, and contrasts invoke vs install, making the tool's role distinct from siblings like authenticate/connect/report_bug. This is a specific, differentiated purpose statement.

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 gives explicit when-to-use guidance: 'prefer invoke for a single/occasional use' and 'Use install only to make an MCP PERMANENT.' It also explains when to use search/describe, subscribe/cancel, report_bug, request_mcp, and the prompt library actions, and notes owner/admin requirements for writes. Clear decision rules and alternatives are provided.

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