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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false. The description adds value beyond these by stating the cost model ("Paid per check (see list_paid_tools)"), the exact return vocabulary (go, no_go, fix), and that it "Never calls the server." That cost and output-shape disclosure goes past what the annotations provide.

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?

Two tightly packed sentences: the first front-loads the usage trigger and the four checks, the second covers the return values, cost, and the no-server-call guarantee. No sentence is wasted or redundant with the schema.

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?

With no output schema, the description appropriately explains the verdict values (go/no_go/fix) and the surrounding workflow. It stops short of detailing what a fix payload contains beyond "what to change," a minor gap for a tool whose parameters are otherwise fully documented.

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 100%, including a fully documented nested last_trip object, so the schema already carries parameter meaning. The description only restates the arguments parameter ("the exact arguments you plan to send") and adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 names a specific verb and scope: it checks that an MCP server answers, whether sign-in is needed, that the tool still exists, and that arguments match the schema. This is a distinct capability no sibling (tool_card, find_tool, verify_lock) plainly duplicates, though it does not explicitly contrast itself with them. An agent can tell what the tool does without opening the 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?

"Use this right before calling a tool on an MCP server you have not used today, with the exact arguments you plan to send" gives a clear triggering condition and timing. It also routes payment questions to list_paid_tools. There is no explicit when-not guidance, but the gating condition is precise enough to act on.

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