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

Goes well beyond the readOnly/openWorld annotations: it discloses that exactly one anonymous request is made, that many listed servers require auth and will therefore fail anonymously (normal, not a fault), and that absence from the registry is not evidence of non-existence. These are the exact misreadings an agent would otherwise make.

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?

Front-loaded with the trigger and return content, then limits, then exclusions. Despite its length, every sentence either routes the agent or prevents a specific misinterpretation; nothing is filler.

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?

No output schema exists, so the description carries the burden and does: it enumerates the returned fields (name, version, publish/update dates, remote endpoints, status) plus the probe result, and pre-empts the two most likely false inferences from that output.

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 coverage is 100%, so baseline is 3, but the description adds real meaning: it clarifies the endpoint contacted is registry-published only, and the schema note that `server` is a name/fragment rather than a URL is reinforced by the narrative, preventing URL-style inputs.

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?

Specific verb+resource: it checks whether a named MCP server is in the official registry, what endpoint it publishes, how current the listing is, and whether that endpoint responds. It also explicitly names the sibling it is not (check_tool_status) and the cases it does not cover, so an agent can route without opening either schema.

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?

Opens with an explicit trigger ("when the user asks about a specific MCP server"), enumerates the four sub-questions it answers, and closes with a "Not for:" list naming security assessment, install recommendation, and catalog checks, redirecting the last to check_tool_status.

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