Compare two saved perf_runs recordings by headline GPU metric, showing absolute and percent change; recordings under 100 frames are flagged as too short to compare.
Compares two saved recordings (names from perf_runs): each headline number, its change and change in %. Recordings with under 100 frames are flagged: too short to compare.
| Name | Required | Description | Default |
|---|---|---|---|
| a | Yes | ||
| b | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With readOnlyHint=true the safety profile is already covered, and the description goes further by disclosing the return shape (headline number, change, change %) and the notable short-recording flagging behavior. It omits error handling for unknown recording names and says nothing about comparison direction, so it is not exhaustive.
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 dense sentences, no filler, with the core capability and its inputs front-loaded and the caveat about short recordings placed last. Every clause 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?
There is no output schema, so the description correctly summarizes the returned metrics, and the annotation covers safety. The remaining gap is procedural: no guidance on parameter ordering or on what happens when a supplied name does not exist.
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 0% — 'a' and 'b' are opaque strings — so the description must carry the burden. It does add real meaning by identifying them as saved recording names originating from perf_runs, but it never says which parameter is the baseline versus the comparison target, leaving the sign of every reported change ambiguous.
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 (compares), a specific resource (two saved recordings), and even summarizes the outputs produced (headline number, delta, delta %). It also distinguishes itself by naming perf_runs as the source of the recording names, so an agent can place it in the perf_* workflow without ambiguity.
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 context is clear: it operates on saved recordings whose names come from perf_runs, and the 'under 100 frames are flagged: too short to compare' clause tells the agent when a comparison is not meaningful. It stops short of naming an alternative or stating an exclusion, hence 4 rather than 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.