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

Annotations only say openWorldHint true and readOnlyHint false, but the description adds crucial behavioral context: invoke runs one-off without installing, writes require owner/admin, invoke returns connect or checkout links for credential/payment gaps, and search/describe flag installation status. This goes well beyond the sparse annotations and discloses side effects clearly, with no contradictions.

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 long (a dense paragraph) but every sentence carries operational information—core flow, invoke vs install, permissions, credential/payment behavior, prompt library. It is front-loaded with the main purpose and avoids fluff, though it could benefit from structured formatting (bullets) to improve scannability. Still appropriately sized for the tool's complexity.

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 has 14 actions, 23 parameters, no output schema, and sparse annotations, the description supplies essential context: how to discover MCPs, how to run them one-off, when to install permanently, permission requirements, and prompt library usage. It does not detail every parameter or action, but covers the main decision paths and edge cases (credentials, payment). Adequate for a complex tool, though some gaps remain.

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 has 23 parameters with 0% description coverage, so the description must compensate. It explains the action parameter's role and implies how mcp_id, tool_id, and arguments are used for invoke, and mentions prompt_vars for prompt filling. However, many parameters like limit, immediate, conversation, prompt_targets, and cancel_reason remain unexplained, leaving the agent guessing at their semantics. Partial compensation, not complete.

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 marketplace as the official catalog and execution layer for MCPs and prompt library, and outlines the core flow (search → describe → invoke). It distinguishes from sibling tools like authenticate, connect, and report_bug by positioning itself as the central discovery/run hub, so the agent understands its unique role.

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?

Explicit guidance is provided on when to use invoke vs install ('prefer invoke for a single/occasional use', 'Use install only to make an MCP PERMANENT'), when to use list_tools, subscribe/cancel, report_bug, and request_mcp. It also notes permission requirements for writes and behavior when credentials/payment are missing, giving clear decision-making criteria.

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