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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered; the description adds genuine value by bounding the blast radius ('every running test' rather than the build itself) and stating the effect timing ('running sessions end immediately'). It still doesn't say what happens to the build record or what occurs when nothing is running.

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 short sentences with zero filler, and the scope statement plus immediate-effect note are both front-loaded where an agent will read them first.

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 one-parameter mutation tool with rich annotations and no output schema, the description covers what is stopped and how fast. A minor gap remains around the resulting build state and the no-op case that idempotentHint only partially resolves.

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?

Single required parameter buildId with 100% schema description coverage, so the schema already carries the semantics and the baseline of 3 applies. The description adds no format, sourcing, or lookup guidance for buildId beyond the scope phrase.

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 ('Stops') with a precisely scoped resource ('every running test in a TestMu AI web automation build'), which implicitly separates it from the single-session stopSession and from deleteBuild. It never names those siblings, so differentiation relies on inference rather than explicit routing.

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 phrase 'every running test in a build' implies the bulk-stop use case and hints that per-session halting belongs elsewhere, but there is no explicit when-to-use, when-not-to-use, or named alternative such as stopSession or deleteBuild.

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