Pass-rate trend

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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false), so the description only needs to add context. It usefully discloses that data is aggregated per run and can be narrowed to a suite, but says nothing about the sampled run window vs. all runs or the shape of the series returned. No contradiction with 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?

A single short sentence with the metric and scope front-loaded and zero filler. It is efficient, though the terseness leaves room for one more clause about the trend window.

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 simple two-parameter read-only query with no output schema, the description covers what is measured and the filter option. It is adequate but leaves return shape (a series of run/pass-rate points) and default behavior implicit.

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%, so both parameters are already documented, and the description's example 'ui.checkout' mildly clarifies the expected dotted suite-name format. The last_n window parameter is not addressed at all in the description, so it adds only marginal value beyond the 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?

States a specific metric (pass rate), its aggregation granularity (per run), its ordering (over time) and its optional scope (overall or one suite). An agent can distinguish it from aggregate siblings like get_run_summary or detect_regressions, though no sibling is named explicitly.

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?

There is no when-to-use guidance, no prerequisites, and no reference to alternatives such as get_test_history (per-test trend) or compare_runs. The agent must infer from the 'over time' phrasing that this is the trend-over-runs view.

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