set_engine_ini_value

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

Annotations declare destructive/idempotent/non-readOnly, but the description adds substantial context beyond them: the write targets the GConfig copy, is flushed to Saved/Config/<Platform>/, is verified via readback, and does not reload already-loaded config. This discloses persistence behavior and a key limitation that annotations alone cannot convey.

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 action is front-loaded, followed by the important caveats and then the return payload. With no output schema present, the explicit 'Returns:' line earns its place, and there is no 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 config-mutation tool with no output schema, the description covers the target store, the flush destination, the verification step, the non-reload limitation, and the return shape. Nothing an agent needs to call it correctly or interpret the result is missing.

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 100%, so all four parameters are already documented in the schema. The description adds only the implicit 'Engine by default' framing for config_file and maps section/key/value into the return shape; it does not add format or validation meaning beyond the schema. Baseline 3 is appropriate.

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 gives a specific verb and resource ('Write one key into the GConfig copy of an INI') and immediately delineates scope by stating it does not edit Config/Default*.ini, which separates it from sibling config tools like set_cvar and set_project_settings_value. An agent can identify exactly what this tool mutates without opening the schema.

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 provides clear operating context and an exclusion ('does not edit Config/Default*.ini', objects already loaded are not reloaded), which tells the agent when the change takes effect. However, it never names an explicit alternative (e.g. use get_engine_ini_value to read back, or set_cvar for console variables), so the routing guidance is contextual rather than directive.

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