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

Annotations only say readOnlyHint=false and destructiveHint=false; the description goes far beyond them by disclosing that invoke runs one-off without installing, writes require workspace owner/admin, installs are permanent and bloat the tool list, and paid/credentialed MCPs return checkout/connect links that require user action before retry. No contradiction 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 long but densely informative, front-loading the core marketplace identity and then walking through the flow in order. It lacks markdown structure or headings, making it feel like a wall of text, but nearly every sentence adds a distinct behavioral fact needed for this 14-action tool.

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 optional parameters and no output schema, the description covers the main actions, side effects, auth requirements, billing behavior, and the prompt-library sub-feature impressively well. It omits semantics for a few actions/parameters (e.g., resume, immediate, tier_slug) and does not describe return shapes, but it is sufficient for an agent to get started and ask targeted follow-ups.

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 carries the burden. It explains most action enum values (search, describe, invoke, install, list_tools, subscribe/cancel, report_bug, request_mcp, prompt actions) and clarifies tool_id selection and prompt variable behavior. However, several parameters like limit, query, immediate, tier_slug, cancel_reason, and report_context remain under-explained despite being part of the 23-parameter schema.

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 clear verb-resource pair: '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 distinguishes itself from narrower sibling tools by framing itself as the catalog/execution hub.

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 strong usage direction: 'prefer invoke for a single/occasional use' vs 'use install only to make an MCP PERMANENT,' and it covers when invoke needs a connect/checkout link. It does not explicitly contrast itself with sibling tools like connect or toolkit_info, but internally it clearly delineates when each action should be used.

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