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

Beyond the sparse annotations (readOnlyHint=false, destructiveHint=false), the description discloses critical behavioral details: invoke runs tools even when not installed, may return connect or checkout links, and performs a one-off install. It also states that writes require workspace owner/admin and that invoke avoids bloating the tool list. These are significant behavioral insights not captured by 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 lengthy but each sentence introduces a distinct, valuable concept: the core flow, the key invoke behavior, install vs. invoke guidance, permission requirements, and the prompt library. It is logically structured but could benefit from bullet points or section breaks to improve scanability. Given the tool's complexity, the length is largely justified.

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?

The description covers the tool's main purpose, key distinctions, and important caveats, making it usable for many common actions. However, with no output schema and undeclared parameter details, the description leaves gaps for less-common actions (e.g., resume, cancel with reasons, get_prompt with prompt_vars). It is reasonably complete for high-level usage but not fully self-contained for all 23 parameters.

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 description indirectly explains some parameters by describing the core flow (e.g., query for search, mcp_id for describe, tool_id and arguments for invoke), and mentions prompt-related parameters for get_prompt/publish_prompt. However, with 23 parameters and 0% schema description coverage, many parameters remain opaque, such as immediate, conversation, prompt_vars, prompt_targets, and report_context. The description only partially compensates for the lack of schema-level documentation.

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' and explains it as the catalog and execution mechanism for MCPs/tools. It specifies distinct actions (search, describe, invoke, install, subscribe, etc.) and differentiates from sibling tools by focusing on marketplace functionality rather than openfinance-specific operations. The core flow is explicitly laid out, making the tool's purpose unambiguous.

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 when-to-use guidance: 'Use install only to make an MCP PERMANENT in the active toolkit... prefer invoke for a single/occasional use.' It also explains when to use subscribe/cancel, report_bug, and request_mcp, and distinguishes in-app catalog functions from prompt library actions. This directly helps an agent choose between marketplace actions and alternative sibling tools.

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