ping

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

With no annotations supplied, the description carries the full burden and does disclose the single most important behavioral trait: the first call scans Bluetooth and takes roughly 3 seconds, which explains apparent latency and discourages redundant calls. It also describes the return payload, though it omits failure semantics (what happens when the link is dead) and does not state that the operation is read-only/non-mutating.

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 short sentences with zero filler: purpose and return value first, then the latency caveat. The most decision-relevant fact for an agent (the 3-second Bluetooth scan) is placed where it will be read.

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?

For a zero-parameter probe with no output schema and no annotations, the description covers purpose, return contents, and the notable first-call cost, which is most of what an agent needs. What is missing is error behavior on a failed link check and any indication of whether the call has side effects.

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 tool takes zero parameters, so the baseline is 4; there is nothing for the description to disambiguate. The description correctly implies the tool is argument-free by describing it as a pure probe.

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?

States a specific verb and object ('检查链路是否活着') and names the exact payload returned (per-table row counts and phone-side protocol version). None of the siblings (water_today, list_todos, disconnect, etc.) is a health-check, so an agent can distinguish this tool from the list without opening any 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?

Usage is implied by the liveness-check framing, but the description never states when an agent should call ping versus simply calling a data tool, nor any preconditions. There is no explicit when-to-use or when-not-to-use guidance, only an implicit 'call this to verify the link'.

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