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

Annotations already indicate this is a mutating, non-destructive, idempotent operation. The description adds useful behavior: errors if the run does not exist, and the stop is not necessarily instantaneous ('once the stop takes effect'), plus the post-condition observable through get_play_status. 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?

Two sentences, front-loaded with the core action, then concise behavioral details. Every sentence earns its place without redundancy or unnecessary filler.

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 low-complexity two-parameter tool with no output schema, the description covers the core action, error behavior, and post-condition, and even points to a verification tool. The main gap is the undocumented projectId semantics, but overall the agent can select and invoke this tool correctly.

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 only 50%: scriptRunId is documented, but projectId has no description and the tool description does not explain it. The description adds no meaning for the required projectId parameter, leaving an important invocation detail to inference.

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 states a specific verb and resource: 'Stop a running play.' It also clarifies the error condition and expected observable outcome, referencing get_play_status, which distinguishes it from related run-management tools like play_script and get_play_status.

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 makes the usage context clear: use this tool to stop a running play, and verify the outcome via get_play_status. It implicitly contrasts with play_script by using 'stop,' though it does not explicitly name alternatives or state when not to use it.

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