read_file_lines

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

With no annotations, the description fully discloses read-only nature, no side effects, auth, or rate limits. It explains clamping and error behavior (silent clamp, throws on to < from) and return contents (size_bytes, est_tokens).

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?

Three sentences: first defines operation, second explains behavior, third gives usage guidance with alternatives. No wasted words, front-loaded with key info.

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 return includes size_bytes and est_tokens. Provides full behavioral details and usage context, making it complete for the agent.

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 coverage is 100%, so baseline 3. The description does not add extra meaning beyond the schema for the parameters themselves (id, from, to). The behavioral context is covered under transparency.

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 the tool returns a 1-indexed inclusive line slice of a file. It distinguishes from siblings like read_section and grep_in_file by specifying alternative use cases.

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 (inspect stack-trace region, chunk of large file) and when not to (prefer read_section if heading known, grep_in_file if pattern known but not line number).

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