Read an app file

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

The description goes beyond the readOnlyHint annotation by explaining the windowing behavior (offset/length, data_base64, next_offset) and the whole-file sha256 hash for reassembly verification. This provides deep insight into the tool's operational behavior.

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 compact but information-dense, efficiently conveying the windowed reading model and reassembly process in a few sentences. The reference to get_app avoids unnecessary repetition while maintaining clarity.

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?

The description covers the essential aspects of windowed reading, including offset/length, data_base64, next_offset, and the whole-file hash for validation. Given the output schema exists and the complexity is moderate, the description is sufficiently complete to guide an agent without ambiguity.

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?

While the schema already describes length and offset, the description adds the crucial windowing semantics ('offset/length select it', 'data_base64 carries exactly that window') that explain how these parameters interact. It also clarifies the meaning of the whole-file hash, adding value beyond the schema's basic parameter descriptions.

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's function with a specific verb+resource: 'Read one file an app has stored'. It also details the windowed byte access mechanism, distinguishing it from other app-related tools like get_app and file_write.

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 indicates the tool is for reading file content and mentions 'same window grammar as get_app' to signal related usage, but it does not explicitly enumerate when to use this tool over siblings. The context is clear enough for a tool specifically named 'file_read'.

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