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

The description adds behavior beyond the annotations by specifying that only queued or in-progress builds can be cancelled and implying a prerequisite status check. It does not contradict the annotations (readOnlyHint=false, destructiveHint=false) and provides meaningful context without needing to repeat structured hints.

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 two sentences long, front-loaded with the primary action, and contains no filler. Every sentence earns its place by covering the action and a prerequisite.

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 one-parameter mutation tool with no output schema, the description covers purpose, state restriction, and a usage prerequisite. It omits postconditions and error behavior, but given the tool's simplicity and available sibling context, it is fairly complete.

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?

The input schema only defines buildId as a string with no description, and schema coverage is 0%. The description does not directly define buildId, but the reference to build_info implies where the ID comes from, offering partial compensation. For a single self-explanatory parameter, this is adequate but not fully explicit.

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 the specific action ('Cancels'), the target resource ('an EAS build'), and the applicable state ('queued or in progress'). This clearly distinguishes it from sibling tools like expo_workflow_cancel and other build-related operations.

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?

It gives explicit usage context by instructing the agent to check the current status with build_info before cancelling. However, it does not explicitly state when not to use it or name alternative cancellation tools, so it falls short of a full 5.

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