打开网址

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

The description states the basic behavior (opens a URL and returns a result) and mentions that it operates 'in a tab' (implying it may navigate an existing tab). The annotation readOnlyHint=false already signals that this is a mutating action, so the description does not need to over-exploit that. However, it does not disclose potential side effects such as navigating away from the current page or losing unsaved state, and it does not explain output details beyond the return fields. The param descriptions give some behavior (tab_id, timeout), but the main description does not go beyond the core action. This is adequate but not particularly transparent.

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 a single, concise sentence that immediately states the core function and the expected return structure. It is front-loaded with the verb and object, and there is no unnecessary wording. It perfectly fits the desired compactness for a tool description.

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 relatively straightforward navigation tool, the description is complete enough: it explains what it does, what it returns, and the key parameters are well-described in the schema. It does not cover edge cases like navigation failures or timeouts beyond the default, but those are minor and the tool is simple. The lack of explicit guidance on when to use it vs. siblings is covered under usage_guidelines, not here. The description adequately covers its context for an agent to invoke it correctly in most scenarios.

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 input schema provides full descriptions for all three parameters (url, tab_id, timeout) with 100% coverage. The description text itself does not add any additional meaning or elaboration about the parameters, such as constraints, dependencies, or examples. Since schema coverage is high, the baseline is 3. The parameter descriptions are clear and functional, but the tool description adds no extra value beyond them.

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 states the tool's function: '在标签页中打开网址，返回导航结果（url/status/ok）' (open a URL in a tab, return navigation result). It specifies the action (open URL) and the resource (URL). However, it does not explicitly distinguish itself from sibling tools like tab_new (for creating a new tab) or refresh, though the tool name 'navigate' and title '打开网址' make the purpose unambiguous. A 5 would require explicit distinction from alternatives.

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 no guidance on when to use this tool instead of other navigation-related siblings such as navigate_back, navigate_forward, refresh, or tab_new. It does not state any conditions, alternatives, or exclusions. The only implied usage is 'open a URL', which is inherent to the action itself, but not an explicit guideline. A score of 3 would require some implied usage context; here there is none beyond the literal description.

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