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

The description adds a useful behavioral warning not present in the annotations: hosts may truncate tool arguments above ~20 KB. It also implicitly indicates a non-read mutation ('Upload'), consistent with readOnlyHint=false. The description does not disclose additional side effects (e.g., whether it replaces an existing file), but the truncation warning provides substantial practical behavioral context beyond 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?

The description is two concise sentences, starts with the core action, then moves to the most critical usage constraint in a compact phrase. Every sentence adds value, and there is no filler or repeated annotation content.

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 provides enough for the basic action and even includes a clever caution about truncation, making it more complete than a bare upload statement. However, with no output schema, no return shape, and limited explanation of the file object or the resulting behavior, it is not fully complete for an agent that needs to know what a successful upload will produce.

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?

The description adds little beyond the schema: 'base64 file' simply echoes the data field description, and 'to a candidate' only restates the id property. With 50% schema description coverage, the description should have clarified the meaning of file or file_name, but it does not go beyond names and the basic data format. It therefore largely fails to compensate for the schema's missing information.

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 ('Upload'), a specific resource ('base64 file to a candidate'), and points to the matched sibling tools such as hires_upload_application_attachment. It leaves no ambiguity that this is a candidate-level file upload rather than an application or generic attachment. This is more than enough for an agent to select it from the sibling set.

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 explicitly warns against using this tool for resumes and names the preferred siblings (hires_create_candidate, hires_update_candidate) when resume_text is available. It does not enumerate the full set of alternatives, such as upload_application_attachment, so the guidance is clear on one important edge case but not exhaustive for all sibling distinctions.

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