preview_file

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

With no annotations, the description carries the burden of disclosing behavior. It states the tool shows the first rows and supports glob/URL paths, which implies read-only behavior. However, it does not mention error handling, file size limits, or output format details. It is adequate but minimal.

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 exceptionally concise with two sentences, front-loaded with the primary purpose. The parameter list is minimal and each element adds value, with no redundant or extraneous information.

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?

Since an output schema exists, return values are already covered. The description successfully conveys the core purpose and parameters, and the tool is simple. However, it lacks explicit guidance on when to prefer this over sibling tools (e.g., describe_file, profile_columns), leaving a small gap in contextual guidance.

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 property descriptions are 0% covered, and the description fully compensates: 'path' is explained as 'File path, glob or URL' and 'rows' as 'How many rows to show (default 20)'. This adds meaningful semantics beyond the bare types and default value in 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?

The description uses the specific verb 'show' with the resource 'data file' and scope 'first rows', clearly distinguishing it from siblings like describe_file (schema/metadata) and profile_columns (statistics). The phrase 'see real values' reinforces the data-inspection purpose.

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 phrase 'so you can see real values' implies a clear use case for inspecting actual data, and the tool's role is evident from its name and siblings. However, it does not explicitly state when not to use it or name alternatives, so it earns a 4 rather than a 5.

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