fetch_file

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

With no annotations, the description carries the burden and does well: it discloses that content is returned decrypted, that bytes arrive base64-encoded in data_base64, and that oversized files are silently unavailable through this path — a failure mode an agent must anticipate. It stops short of stating auth requirements or the error behavior when a name doesn't exist.

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?

Front-loaded with purpose and prerequisite, then the return shape, then the size caveat. The shell one-liner for decoding is practical but slightly instructional padding; the definition is otherwise tight for the amount of genuinely useful information conveyed.

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 two-parameter read tool with an output schema, this covers purpose, prerequisite, return format, and the large-file escape hatch — everything needed to call it correctly. The remaining gaps (folder scoping, not-found behavior) are minor since the schema and output schema cover the structured side.

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 both 'name' and 'folder' are already documented in the schema. The description reinforces that the name must match what list_files reported but adds nothing about the optional folder parameter, so it neither compensates nor detracts. 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 ('Retrieve one of the user's stored files, decrypted, by name') and explicitly separates the resource from a confusing sibling ('Files live separately from notes'). An agent can distinguish it from recall/remember without opening the schema.

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?

Prescribes a prerequisite ('Call list_files first to find the name') and gives an explicit exclusion with an alternative ('Very large files are not inlined; retrieve those from the web console or the REST /file/download endpoint instead'). Both the when and the when-not are stated.

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