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

Annotations note readOnlyHint=false and openWorldHint=true, but the description adds important behavioral context: invoke can run MCPs without installation, returns connect/checkout links for auth/payment, and requires workspace owner/admin for writes. It also explains side effects like not bloating the tool list. Minor gaps: no explicit mention of idempotency or failure modes, but the description is quite transparent.

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 comprehensive, covering many actions and scenarios, but it is a single long paragraph without clear breaks or front-loaded summary. It earns its place for the most part, but could be more scannable with lists or sectioning. It is not overly verbose relative to the tool's breadth.

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 23 parameters prescription, no output schema, and no per-parameter documentation, the description is remarkably complete: it explains the core flow, edge cases (auth, payment, writes requiring admin), and the prompt library. Minor omissions: no detail on parameters like 'limit', 'immediate', or 'tier_slug' beyond their existence, but the description covers the main usage comprehensively.

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 description coverage is 0%, so the description must compensate. It explains key parameters like action (lists all enum values with semantics), mcp_id, tool_id, arguments, and prompt-related params. It does not detail every parameter (e.g., limit, immediate, tier_slug), but covers the most critical ones, enabling correct usage.

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 is 'the official mcp.ai marketplace' for discovering and running MCPs, enumerates its primary actions (search, describe, invoke), and distinguishes it from sibling tools like authenticate and connect. It covers the full scope of the marketplace and the prompt library, providing a specific verb+resource for each action.

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: use 'invoke' for one-off runs even if not installed, use 'install' for permanent toolkit inclusion, and states 'prefer invoke for a single/occasional use'. It also details the core flow (search → describe → invoke) and covers edge cases like auth and payment links, which clarifies when to use each action.

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