Write a file to the local filesystem.

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

No annotations provided, so description bears full burden. It discloses overwrite behavior, the read-first requirement (and that failure occurs otherwise), and preference for Edit. Could mention directory creation or error handling, but covers key behavioral traits well.

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?

One clear introductory sentence followed by bullet points with zero redundancy. Every sentence contributes meaningful guidance. Front-loaded with purpose.

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?

No output schema exists, but no return value explanation needed. Description covers prerequisites (read first), alternatives (Edit), and prohibitions (markdown/emojis). Complete for a file-write tool of moderate complexity.

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 covers 100% of parameters with descriptions. The tool description adds no additional meaning beyond the schema (e.g., no format constraints or examples). 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 begins with 'Writes a file to the local filesystem,' a clear verb+resource statement. It distinguishes from siblings by specifying when to use Write vs Edit (modifications) and Read (must read first for existing files).

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 states when to use (create new files or complete rewrites), when to avoid (prefer Edit for modifications), and prerequisites (must read file first if existing). Also includes prohibitions on markdown and emojis unless requested.

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