file_read

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

No annotations exist, so the description carries the burden. It usefully discloses output shape (line-numbered, middle-truncated at max_output_bytes) and negative-index semantics, which is real behavioral context. It says nothing about error behavior for missing files, permissions, or how conflicting modes (e.g. start_line vs head_lines) resolve.

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?

One dense, front-loaded sentence with the primary capability ('Read a file') first and the qualifiers following. It is information-rich with no filler, though the em-dash chain makes it slightly harder to scan than a short bulleted breakdown would be.

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 14-parameter tool with no annotations and no output schema, the description covers the headline modes and truncation behavior adequately. It stops short of explaining error handling, parameter conflicts, or binary/base64 handling, leaving some gaps that the schema only partially fills.

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?

With 100% schema description coverage, the schema already documents all 14 parameters including defaults and enums; baseline is 3. The description reinforces the most important ones (start_line/end_line negatives, head_lines/tail_lines, match regex) but adds no syntax or precedence detail beyond the 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?

States a specific verb+resource ('Read a file') and immediately enumerates the access modes (line range, head/tail, regex match), so an agent knows exactly what capability it offers. The 'middle-truncated at max_output_bytes' and 'line-numbered' phrasing further pins down the behavior in a way that distinguishes it from raw shell reads.

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?

It gives a clear usage rationale ('far cheaper than reading a whole file') that steers the agent toward partial reads rather than whole-file reads. However, it never names the sibling tools (search_text, search_files) or states when those should be preferred over match= mode, so no explicit exclusions are provided.

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