count_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 that the tool returns sixteen specific metrics, including behavioral details like line-ending style detection and reading time estimates. This gives insight into the tool's output behavior, which is largely sufficient for a non-destructive, pure calculation 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?

The description is two sentences, packed with specific detail and no filler. It front-loads the core purpose and then lists notable metrics, making it concise and informative.

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 one-parameter tool, the description fully covers its functionality and return values. It enumerates the types of metrics returned, which is especially important given there is no output schema. The description is complete for an agent to understand the tool's capabilities without additional context.

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?

The input schema has 100% coverage with a clear description of the 'text' parameter (UTF-8, max 1 MB). The tool description does not add additional parameter semantics but reaffirms the purpose. Baseline of 3 is appropriate given the schema's completeness.

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 uses a specific verb (Count) and clearly identifies the resource (a chunk of text) and the scope (lines, words, sentences, paragraphs, characters). It distinguishes itself from sibling tools by detailing the sixteen metrics returned, including unique features like duplicate-line detection and line-ending style, making it unambiguous.

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?

The description implies usage for text analysis and counting but does not explicitly state when to use this tool versus alternative text utilities like stats or text_diff. It provides clear context about what it does, but lacks explicit when-to-use or when-not-to-use guidance.

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