chrome_download_statusCheck whether the local download bridge, Chrome extension connection, and outbound circuit breaker are active; inspect extensionConnected when downloads stall.
查本机下载桥是否可用、扩展有没有连上、出站熔断状态。排查第一步就敲它。插件冷启动最长约 30 秒（Chrome 扩展后台定时器官方下限），任务没动静先看这里的 extensionConnected。
| Name | Required | Description | Default |
|---|---|---|---|
| stateDir | No | 状态目录（默认按 endpoint.json 的位置） |
Changes observed during successful MCP inspections.
v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnly, idempotent, non-destructive), so the bar is lower, and the description adds genuinely useful behavioral context: extension cold start can take up to ~30s due to Chrome's background timer floor, explaining why extensionConnected may read false initially, plus the naming of the extensionConnected field. It does not explain the circuit-breaker semantics or the response structure in depth.
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?
Three sentences, front-loaded with what the tool checks, followed by when to use it and the cold-start caveat. Every sentence contributes, though the parenthetical about the Chrome timer is slightly dense.
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 status tool with no output schema, the description tells the agent what conditions to inspect and names one output field (extensionConnected), which is enough to call it correctly. A fuller picture of the returned shape would push this higher, but no output schema is present to rely on.
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% and the single optional stateDir parameter is documented there, so the schema carries the load. The description adds no syntax, default, or format detail about stateDir, matching the baseline 3 for high-coverage schemas.
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 states a specific verb (查/check) plus three concrete resources: whether the local download bridge is available, whether the extension is connected, and the outbound circuit-breaker state. This clearly distinguishes it from the action-oriented siblings (download, pause, resume, cancel) that likely appear as names in the sibling list.
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?
It gives explicit when-to-use guidance: '排查第一步就敲它' (this is the first step in troubleshooting) and '任务没动静先看这里' (if a task isn't moving, look here first). That is strong context, though it does not name a sibling alternative or an exclusion case, so it falls short of a full 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.