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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds value by disclosing what kind of information the tool retrieves (status, errors, artifacts), which is not apparent from the schema or annotations alone. This gives the agent an expectation of the return content.

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, with the primary purpose front-loaded and the usage guidance in the second sentence. There is no extraneous information, making it highly concise and well-structured.

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?

The tool has a single parameter, no output schema, and good annotations. The description covers the return content (status, errors, artifacts) sufficiently for an agent to understand what to expect. It lacks some detail about response format, but given the low complexity, it is nearly 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?

Schema description coverage is 0%, so the description must compensate. It mentions 'by ID', which clarifies that buildId is the build identifier, but does not provide additional format or source guidance. For a single simple parameter, this is adequate but not enlightening.

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 uses the specific verb 'Fetches' and clearly identifies the resource as a specific EAS build by ID with status and detailed information. It distinguishes from sibling tools like expo_build_list (lists builds) and expo_build_logs (logs) by focusing on a single build's status, errors, and artifacts.

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 explicitly states 'Use this to check build status, errors, artifacts, and other details,' providing clear context for when to use this tool. It does not explicitly mention alternatives or exclusions, but the use case is clear enough to differentiate from siblings.

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