append_file

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

With no annotations provided, the description carries the full behavioral burden, and it delivers meaningful context: it discloses the line-ending insertion edge case ('Inserts the file's line ending first when the file does not already end with one') and warns about concurrent-call hazards, implying non-atomicity. It does not mention failure behavior for missing files, which keeps it from a 5.

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 compact and front-loaded: purpose first, then the line-ending nuance, then the critical concurrency warning, then a working example. Every sentence earns its place — there is no filler or repetition of the schema.

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 simple two-parameter tool with no annotations and no output schema, the description covers the essential ground: purpose, edge-case behavior, concurrency hazard, an atomicity alternative, and a usage example. The main gaps are the missing-file failure behavior and what the tool returns, but these are minor for a simple append operation.

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 0%, so the description must compensate, and it does: 'Append content to an existing file' maps content and path directly, and the example {"content":"#[test]\nfn new_test() {}\n","path":"tests/test.rs"} demonstrates concrete formats for both parameters and clarifies that path must point to an existing file. It lacks deeper parameter nuance (e.g., size limits or encoding) but compensates adequately.

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 opening sentence uses a specific verb plus resource: 'Append content to an existing file.' The word 'existing' explicitly distinguishes it from create_file, and 'append' contrasts with prepend_file and replace_text. The edge-case detail about line endings and the concrete example reinforce the tool's exact function.

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 clear context for when to use the tool (append to an existing file) and gives an explicit exclusion: 'do NOT issue concurrent calls targeting the same file.' It also routes to an alternative, 'use execute_plan for multi-op atomicity.' It stops short of a 5 because it does not explicitly contrast with direct siblings like prepend_file or create_file.

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