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

Annotations already indicate a safe read-only, idempotent operation. The description adds meaningful behavioral details: the 256 KB limit, refusal rather than truncation for non-text or oversized files, and the default-to-newest-version behavior with consistency to read_app's version listing. No contradiction with annotations.

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?

Four compact sentences, each earning its place: main purpose, usage trigger, size/type constraint, and version behavior. The most important scoping information is front-loaded.

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 read-one-file tool with no output schema, the description is complete: it specifies the return type (text), size cap, refusal behavior, and version selection. The agent has enough information to invoke it correctly.

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%, so the schema already documents app_id, path, and number. The description adds useful cross-tool meaning for the number parameter: the version is the same one read_app lists, which helps the agent pick the correct version identifier.

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 operation: read one file out of an app as text, at most 256 KB. It also distinguishes itself from read_app by specifically targeting files omitted with content_omitted and by fetching a single file without the rest of the app.

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 explicitly tells when to use the tool: for files that read_app left out due to the answer budget, or to fetch a single file. It also warns that non-text and oversized files are refused, giving the agent clear criteria for avoiding misuse.

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