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

For a tool with readOnlyHint false, the description discloses side effects and nuanced behaviors: invoke runs a tool 'without adding the MCP to the toolkit', can return a connect link or checkout/top-up link, and flags installed status on search/describe. It also clarifies the one-off install behind invoke and the prompt library's publish flow, providing substantial context beyond 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 lengthy single paragraph but packs high information density. It front-loads the primary purpose, then walks through the core flow, key exceptions, auth requirements, and the separate prompt library feature. While not bulleted, every sentence adds necessary behavioral detail; a few could be streamlined, but it remains efficient 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 no output schema, the description provides return-relevant details for major actions (describe returns full profile, invoke returns connect/checkout links, get_prompt returns full text with vars filled, publish_prompt returns shareable link). It also covers permission prerequisites and the permanent vs. one-off distinction. Some actions like `list_tools` only get a terse 'lists what is callable right now', but overall it is sufficient for a tool of this breadth.

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?

The input schema has 23 parameters with 0% description coverage, but the description compensates by explaining the semantics of `action` values (search, describe, install, invoke, list_tools, search_prompts, get_prompt, publish_prompt, etc.) and the flow between them. It does not define every parameter (e.g., `immediate`, `tier_slug`, `cancel_reason`), but the action-focused explanation covers the majority of usage scenarios.

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 'The official mcp.ai marketplace — the in-platform catalog of every MCP/tool, AND the way to run them,' which clearly identifies the tool's dual role. It further enumerates capability requests and the core search/describe/invoke flow, distinguishing its purpose from sibling tools like authenticate or connect.

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 guidance: 'Core flow: action=search discovers MCPs by intent → describe returns one MCP's full profile... → invoke RUNS that tool.' It also contrasts `invoke` (one-off) with `install` (permanent): 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It additionally notes permission requirements ('Writes require workspace owner/admin').

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