Set JavaScript breakpoint

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

Annotations already convey that the tool is non-read-only, non-idempotent, and non-destructive, lowering the burden on the description. The description adds that the breakpoint is set 'through the local Chromium debugger,' suggesting session-scoped behavior, but does not disclose side effects such as whether breakpoints persist, whether setting the same breakpoint twice replaces or duplicates it, or what happens when a breakpoint is hit. This is adequate for a simple tool but adds little beyond the annotations.

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, front-loaded sentence that opens with the action and adds only necessary modifiers: source URL, one-based line number, and local Chromium debugger. There is no filler, and every word earns its place.

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 straightforward breakpoint-setting action, the core operation is covered, and the presence of an output schema means return-value details need not be in the description. However, the description leaves the required sessionId unexplained and offers no routing guidance among the debugging-related sibling tools. The tool is callable but assumes the agent already understands session management and sibling distinctions.

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 0%, so the description must carry the semantic burden for the four parameters. It explains 'sourceUrl' and 'line' by mentioning 'source URL and one-based line number,' but it entirely omits the required 'sessionId' and the optional 'column.' With a required parameter unexplained and only half the parameters semantically covered, the description only partially compensates for the schema's lack of descriptions.

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 uses a specific verb ('Set') and resource ('a breakpoint'), and further specifies the addressing mechanism ('source URL and one-based line number') and environment ('local Chromium debugger'). This makes the tool's purpose unmistakable and clearly distinct from sibling tools like web_debug_evaluate, web_debug_control, and web_replay_seek, none of which set breakpoints.

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 implies usage guidance by defining the action, but it does not explicitly state when to use this tool versus alternatives like web_debug_control, web_next_inspect, or web_debug_evaluate. There is no when-not-to-use guidance, naming of alternatives, or prerequisite conditions beyond the implicit 'local Chromium debugger' context.

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