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

The description goes far beyond the annotations, which only provide generic hints (readOnlyHint=false, etc.). It discloses side effects: 'invoke works even when the MCP is NOT installed... without bloating the tool list'; auth implications: 'Writes (install/uninstall/subscribe/cancel and the one-off install behind invoke) require workspace owner/admin'; and failure modes: 'invoke returns a connect link... checkout/top-up link (the user opens it, then you retry).' No contradictions found 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 a single dense paragraph that covers a lot of ground, and every sentence does add functional value. However, it is not well-structured for rapid parsing—no list breaks, headers, or grouping of conceptually related actions (search/describe/invoke vs. install/uninstall vs. prompt library). This hurts scannability and makes the tool harder to grasp at a glance, despite the high information density.

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 complexity (14 action values, 23 optional params, no output schema), the description is thorough. It explains the end-to-end flow, the one-off vs. permanent distinction, auth requirements, billing behavior, prompt library functions, and even the fact that search/describe flag installation status. It covers essentially all major behavioral contexts an agent would need to select and invoke actions 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?

Schema description coverage is 0%, so the description must compensate. It partially does by explaining action values and the role of tool_id/arguments in the flow. However, many parameters (limit, immediate, tier_slug, cancel_reason, prompt_*) are never explained, leaving the agent to infer or guess. The description adds meaning for the core params but not for the full 23-parameter surface, so it doesn't fully compensate for the absence of schema descriptions.

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 opens with a specific, verb-driven statement: 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them.' It clearly enumerates distinct sub-functions (search, describe, invoke, install, list_tools, etc.) and contrasts with siblings like authenticate or connect by positioning itself as the catalog/execution layer. The purpose is unmistakable and well differentiated.

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 usage guidance is embedded throughout: 'prefer invoke for a single/occasional use' and 'Use install only to make an MCP PERMANENT' directly tell when to choose one over the other. It also lists example use cases ('Covers capability requests like...') and describes the core flow (action=search → describe → invoke), giving the agent a clear decision path. No sibling alternatives are named, but the tool's own internal actions are well differentiated.

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