replay

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

With no annotations, the description carries full burden. It discloses that the tool opens a browser with an HTML diff report, which is non-destructive. It does not mention any permissions or side effects, but the behavior is well-described and consistent with a read-only viewer.

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 three sentences, each adding distinct information: purpose, content of viewer, and browser behavior. No unnecessary words, front-loaded with the key action, and well-structured.

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?

Given no output schema and no annotations, the description covers the core functionality and parameter behavior. It does not explain return values or error cases, but as a viewer tool that opens a browser, the output is self-evident. Slight gap in explaining prerequisites (e.g., requires prior test run), but overall sufficient.

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 coverage is 100% with clear descriptions for all three parameters: test_name (optional), test_path (default), no_browser (controls auto-open). The description adds context about 'specific test' and 'opens automatically', aligning with parameters but adding minimal value beyond schema.

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 it opens a trajectory diff viewer for a specific test, showing side-by-side HTML comparison of baseline vs current behavior. This differentiates it from siblings like compare_agents (compares agents) or run_check (runs checks), as it focuses on viewing diffs for a specific test.

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 for viewing diffs after running a test, and mentions automatic browser opening. However, it does not explicitly state when to use this tool versus alternatives, such as when to use compare_agents instead. The purpose is clear but guidance on exclusion is lacking.

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