chmod

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

Annotations already indicate destructiveHint=true. Description adds that it 'modifies filesystem permission bits' (confirming destructiveness) and mentions returning JSON with old and new mode values, and the --dry_run option, providing useful behavioral context beyond 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?

Description is concise: three sentences covering purpose, destructiveness, dry-run, return format, and alternatives. No unnecessary words, front-loaded with key 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?

Despite no output schema, the description explains the return format (JSON with old and new mode), covers destructive behavior, usage guidance, and alternatives. Complete for a tool with well-documented parameters.

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?

All 5 parameters have full schema descriptions (100% coverage). The description repeats some schema information (e.g., octal mode examples) but does not add significant new meaning beyond what is already in the input 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?

Clearly states 'Change file permissions using octal modes' as the primary action, and distinguishes from sibling tools by mentioning 'chown' and 'chgrp' for ownership changes.

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 ('control read/write/execute access'), when not to use ('Not for ownership changes'), and provides alternatives ('use 'chown' or 'chgrp'). Also mentions --dry_run for previewing.

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