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

The description goes well beyond the annotations by disclosing that invoke works even when the MCP is not installed, returns connect links for missing credentials, returns checkout/top-up links for insufficient wallet balance, and requires workspace owner/admin for writes. This is valuable behavioral context not present in readOnlyHint/openWorldHint/idempotentHint/destructiveHint.

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 information-dense and front-loaded with the core purpose, then follows a logical flow: discovery, execution, installation, billing, auth, and prompt library. It lacks headings or bullet structure, which slightly hurts scannability, but every sentence contributes substantive guidance and avoids fluff.

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 (23 parameters, 14 actions, no output schema, sparse annotations), the description is remarkably complete. It covers the main flow, one-off vs permanent execution, credential and payment edge cases, permission requirements, billing actions, and the prompt-library subsystem. It even describes behavioral outcomes like connect links and checkout links, compensating well for the absence of an output schema.

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 schema has zero description coverage across 23 parameters, but the description partially compensates by explaining action=search, describe, invoke, install, subscribe/cancel, list_tools, and the prompt actions. However, it does not define parameter-level details such as arguments format, prompt_vars JSON, immediate, tier_slug, or how query/limit interact with search. The agent must infer much of the parameter semantics from parameter names alone.

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 tool as the official mcp.ai marketplace, a catalog of MCPs/tools and a way to run them. It specifies concrete actions like search, describe, invoke, install, and prompt-library functions, and distinguishes itself from siblings by highlighting its unique role in discovery, one-off execution, and permanent installation.

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 an explicit core flow: search discovers MCPs, describe returns profiles, and invoke runs the chosen tool. It gives strong when-to-use guidance, including 'prefer invoke for a single/occasional use' and 'Use install only to make an MCP PERMANENT,' plus clear separation for billing actions like subscribe/cancel and prompt-library searches.

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