expand

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

Annotations already declare readOnlyHint=true, so the agent knows it's safe. The description adds that it does not modify files, returns JSON by default, and supports --raw for plain output, as well as configurable tab stops. This extends beyond annotations without contradiction.

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 four sentences, each earning its place. It front-loads the core purpose, then adds important details about output format, configuration, and alternative tools. No redundant or filler content.

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 conversion tool without an output schema, the description fully covers what the tool does, its output format (default JSON, optional raw), key parameters (tab stops), and its niche (normalizing indentation). It also provides cross-reference to the reverse tool, making it contextually complete.

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?

Input schema has 100% coverage with descriptions for all 5 parameters. The description does not add significant new info about parameters beyond what the schema provides, but it reiterates key usage points (tab stops, raw output). Baseline of 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 clearly states 'Convert tab characters to spaces in files or stdin' with a specific verb and resource. It distinguishes itself from sibling 'unexpand' by mentioning the reverse operation, ensuring the agent knows which tool to select.

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 provides usage guidance: 'Use to normalize indentation to spaces. Not for converting spaces to tabs — use 'unexpand' for the reverse operation. See also 'unexpand'.' This tells when and when not to use, and names the alternative tool.

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