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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds substantial behavioral context beyond annotations: the 5 MB size cap, the default UTF-8 output and the base64 fallback via as_text, and the auth requirements (token + live sandbox_id). This prevents misuse for large payloads.

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 a single dense paragraph that front-loads the core purpose, then the alternative, then the requirements. It is well-structured, though it slightly repeats 'max 5 MB' and 'get_download_url' at the end, which is minor redundancy.

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 tool with full schema coverage, no output schema, and safety annotations already in place, the description covers everything an agent needs: scope, size limit, output format, auth prerequisites, and the correct alternative for larger files.

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 description coverage is 100%, so the schema already fully documents path, sandbox_id, and as_text, including the base64 behavior and the absolute-path constraint. The description mostly repeats that information without adding new syntax or edge-case meaning, making the baseline 3 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 states a specific verb and resource: reading a small file from a sandbox into the conversation, with the output representation (UTF-8 vs base64). It explicitly distinguishes itself from the sibling get_download_url for large files, so an agent can route correctly without opening schemas.

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 explicit when-to-use (small files, max 5 MB) and when-not (build artifacts, archives, binaries, anything big) and names the alternative (get_download_url) with the reason (short-lived link, avoid base64 in context). Prerequisites (token + live sandbox_id) are also stated.

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