file_write

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

With no annotations, the description carries the full burden. It usefully discloses side effects: parent directories are created and existing EOL style is preserved, and create_new fails on existing files. However, it never states that the default 'overwrite' destroys existing content irreversibly, nor anything about permissions or failure behavior for the other modes.

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?

Three short sentences, zero filler, with the core action first and the alternative-tool routing last. Every clause carries information.

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 7-param mutation tool with no annotations and no output schema, the description covers the destructive default, the mode failure case, and side effects like directory creation and EOL preservation. The main remaining gap is not flagging the data-loss risk of the default overwrite mode.

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 adds semantics the schema lacks: the per-mode behavior of overwrite/append/prepend and the failure condition for create_new, which the enum only labels 'Default overwrite'. Other params (eol, encoding, create_dirs) are left entirely to the schema.

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 ('Write a whole file') with explicit scope ('whole', as opposed to partial edits), and names the sibling it is not by routing to file_edit. An agent can distinguish it from file_edit or shell-based writes 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?

Explicitly routes the agent: 'For a small change to a big file use file_edit.' It also documents the discriminating condition for create_new ('fails if it exists'). No guidance on when-not to use it versus shell_bulk or other write paths, but the primary alternative is covered.

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