engine_map_units

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

With no annotations, the description must disclose behavior, but it only states an output concept ('Function signatures of the unit files') without confirming side effects, read-only status, caching behavior, or the role of the reload and source parameters. It does not contradict any annotations because none are provided.

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 short and avoids filler, which helps readability. However, the fragment 'Function signatures of the unit files - what a module may call' is more of a gloss than a structured definition and sacrifices clarity for brevity.

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?

There is no output schema and no annotation coverage, so the description is the only source of grounding. It fails to explain what the returned signatures look like, how reload changes behavior, whether source is mutually exclusive with all units, or any other operational context the agent would need.

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 50%: source is described in the schema, but reload is not. The description does not compensate for reload or clarify how it affects the returned signatures, so an agent gets little help understanding the optional boolean's meaning or the relationship between source and the overall result.

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 identifies the resource (unit files) and the subject (function signatures), and the phrase 'what a module may call' adds some semantic context. However, it is a noun phrase rather than an explicit verb+resource statement, and it does not clearly differentiate itself from the sibling engine_map_tree or other map-like tools.

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?

There is no guidance about when to use this tool instead of a sibling, and no mention of prerequisites or context such as whether a source file must be provided. The description implies it is for inspecting callable function signatures, but leaves appropriate-use conditions entirely to inference.

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