read_file_lines

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

With no annotations provided, the description carries the full burden. It discloses read-only nature, no side effects/auth/rate limits, silent clamping for out-of-range bounds, throws on to<from, and return contents (snippet plus size_bytes and est_tokens). This is exemplary transparency for an unannotated tool.

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?

Six sentences, each earning its place: core action, edge cases, side-effect declaration, return shape, use case, and sibling alternatives. Front-loaded with the primary verb and resource. No filler or repetition.

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 read tool with 3 required params and no output schema, the description fully covers purpose, behavioral quirks, return values, and usage context. Nothing critical is missing; the tool is simple enough that this is 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?

Schema description coverage is 100%, so baseline is 3. The description reiterates 1-indexed inclusive semantics and adds clamping behavior tied to from/to, but does not materially expand parameter meaning beyond the schema. No missed parameters or ambiguity.

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 starts with a specific verb+resource+scope: 'Return a 1-indexed inclusive line slice of a file.' It clearly distinguishes from siblings by naming exact alternatives (read_section, grep_in_file), making the tool's unique purpose unmistakable.

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: 'Use to inspect a stack-trace region or a chunk of a large file without pulling the whole body.' It also names alternatives with specific conditions: 'Prefer read_section if you know the heading, grep_in_file if you know a pattern but not the line number.' This is exactly what the rubric requires.

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