read_file

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

Without annotations, the description fully discloses behavior: 'Read-only; no side effects, auth, or rate limits.' It also notes the error condition 'Throws if ID is unknown' and mentions returned fields, providing comprehensive behavioral context.

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 highly concise, using two sentences to convey purpose, behavior, and alternatives. Every sentence adds value, and the structure is front-loaded with the core action and read-only guarantee.

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 1-param tool with no output schema, the description covers all essential aspects: purpose, behavior, error handling, return fields (with helpful context like est_tokens), and usage guidance. It is complete for agent decision-making.

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% with one parameter 'id' described as 'File ID'. The description adds minimal additional semantics beyond this, though it does clarify that the ID is used for retrieval and validation ('Throws if ID is unknown'). Baseline 3 is appropriate.

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 explicitly states 'Read one file's full body and metadata by ID,' clearly defining the verb (read), resource (file), and method (by ID). It also distinguishes from sibling tools by specifying when to use alternatives.

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 provides explicit usage guidance: 'Use for a single known file.' It then lists alternatives with conditions (describe_file for inspection without body tokens, read_files for batches, etc.), covering when-to-use and when-not-to-use.

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