Write a config file

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

Annotations already flag destructive/openWorld, but the description adds the crucial behaviors: HA's config check runs after the write and restores prior contents on failure, the result reports verified/rolled-back status, the write replaces the entire file, changes require a restart or reload, and the ha:files scope is required. These are exactly the operational traits an agent needs for a destructive write and are not derivable from the annotations.

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?

Multi-paragraph but front-loaded, with the highest-risk facts (checked-and-reversible, whole-file replacement) emphasized and bolded. Slightly redundant with the schema on the verify default, but that repetition is defensible for a destructive tool where a mistake is costly.

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 the description compensates by stating what the result reports (verified vs rolled back). It also covers scope requirements, restart semantics, binary vs text handling, and preferred alternatives, so nothing an agent needs to call this correctly 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 coverage is 100%, so the baseline is 3, but the description meaningfully augments it: it clarifies that with encoding='base64' the content is the base64 of the bytes rather than the bytes, and explains why verify defaults off for base64 (check_config only validates YAML). The instance_id cross-check against the session's target is also described in more operational terms than the schema alone.

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?

States a specific verb and resource (write a file under Home Assistant's config directory) and immediately distinguishes itself from siblings by naming ha_read_config_file, ha_check_config, ha_set_helper, and ha_set_automation. An agent can tell it apart from ha_edit_config_file and ha_delete_config_file without opening any 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?

Gives explicit when-to-use and when-not-to-use guidance: prefer purpose-built tools (ha_set_helper, ha_set_automation) where one exists, read first with ha_read_config_file before replacing the whole file, pass verify=false only when writing interdependent files and then call ha_check_config yourself. Alternatives and their reasons are named.

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