Get a file

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

Annotations already declare read-only, idempotent, non-destructive, non-open-world behavior, and the description correctly does not restate that. It does add genuinely new behavior: the signed download link's ~60 s expiry and the warning to consume it immediately, which no annotation conveys. Not describing not-found/error behavior or whether links can be re-fetched keeps it short of a 5.

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?

Three short sentences, front-loaded with the core capability, then the conditional 'detailed' behavior and its time constraint, then the return shape. No filler and the most actionable warning (use the link at once) is not buried.

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 two-parameter read with a full schema and an output schema, the description covers purpose, the format branch, the expiry hazard, and the structuredContent wrapper. Only error/not-found handling is unaddressed, which is minor at this complexity.

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% and the enum descriptions already explain concise vs. detailed including the 60 s validity, so the description's mention of 'detailed' is largely duplicative of structured data. The id format and required-ness are handled entirely by the schema, so the baseline 3 applies.

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?

States a specific verb and resource ('Fetches one file's details by id') and enumerates exactly what comes back: name, kind, type, size, description, and attached records. The 'by id' framing plus the single-object scope distinguishes it cleanly from the sibling heliyos_files_list.

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?

Gives a real operational constraint for one path — the detailed download link expires in about 60 s, 'so use it at once' — but never says when to prefer this tool over heliyos_files_list, heliyos_files_delete, or heliyos_records_get for attached records. The only id-sourcing hint lives in the schema ('File id from heliyos_files_list'), not the description.

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