build_sim

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

No annotations are provided, so the description carries the full behavioral disclosure burden. It states the compile-only nature and the absence of a launch, which is the core behavior. However, it omits other potentially relevant details like side effects (e.g., DerivedData changes), prerequisites (e.g., an available simulator), or what exactly is produced.

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 a single short sentence with the tool/action front-loaded. Every word adds value—the scope ('iOS sim') and the key constraint ('compile-only, no launch') are included with zero waste.

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 basic build tool, the core function is clearly conveyed, and the schema covers two of three parameters. However, with no annotations, no output schema, and the description not addressing `buildForTesting`/`testProductsPath` usage scenarios or any environmental requirements, the overall context remains somewhat incomplete though adequate for simple use.

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 high (67%), with `buildForTesting` and `testProductsPath` already described in the schema. The description itself adds no parameter-level detail; `extraArgs` remains undocumented both in the description and schema, but the high schema coverage justifies a baseline 3.

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 specifies a clear verb ('Build') and resource ('iOS sim'), with an explicit scope modifier '(compile-only, no launch)' that distinguishes it from the sibling `build_run_sim`. This gives an unambiguous purpose.

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 parenthetical '(compile-only, no launch)' clearly signals when to use this tool: when a build without launching is desired. It does not explicitly name the alternative `build_run_sim`, but the exclusion is evident from the 'no launch' phrase, providing clear context with no misleading guidance.

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