prepend_to_file

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

The description discloses two valuable behavioral traits: content is inserted as byte concatenation (no automatic newline handling) and the write is atomic. However, with no annotations, it omits other important details like file-existence behavior, permissions, and error/return semantics, leaving gaps for an agent.

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 extremely concise, using one statement and two fragments to convey core action, byte-level behavior, and atomicity. Every element serves a purpose and is front-loaded, with no redundant or fluffy language.

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?

Although the schema fully covers parameters, the description lacks usage differentiation from sibling tools, error handling for missing files, and return-value details (no output schema exists). The atomicity and byte-level semantics help, but an agent still has open questions for reliable invocation.

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?

The schema already thoroughly documents all parameters (100% coverage), including the byte-for-byte semantics of content and the ensure_newline_after behavior. The description's mention of 'Optional ensure_newline_after' merely repeats schema information and adds no extra meaning.

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 clearly states the action ('Insert content'), the resource ('a file'), and the specific scope ('at the very beginning'), which distinguishes it from append at a glance. However, it does not explicitly contrast with sibling tools like append_to_file or insert_at, so it misses the top score.

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 description provides no guidance on when to use this tool versus alternatives such as append_to_file or insert_at, nor any prerequisites (e.g., whether the file must exist) or exclusions. The only hint is the location 'very beginning,' but no direct usage context is given.

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