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

Annotations already declare the safety profile (readOnly=false, destructive=false, idempotent=false, openWorld=false). The description usefully adds the permanence/destination context (the file is stored on a contact's record), which the annotations do not convey, but it says nothing about duplicate uploads for a non-idempotent write or about the human-approval flow implied by approval_id.

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?

Two short sentences with no filler, and the trigger condition is front-loaded. The first sentence is a subordinate clause fragment with no main verb, which reads slightly awkwardly, but nothing is wasted.

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?

With an output schema, full parameter coverage, and annotations present, most structured context is carried elsewhere. The remaining gap is that the definition never clarifies the relationship to attachments.upload or whether the file is retrievable/listed afterward (documents.list exists), leaving the agent to choose between two near-identical upload tools.

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 all four parameters (including approval_id and its single-use semantics) are already documented in the schema. The description only restates that content is base64-encoded, adding no new syntax or format detail beyond what is given.

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 gives a specific verb ("Uploads") and a clear target (a file that belongs on someone's record), plus the input mechanism (base64-encoded content), so an agent knows exactly what the tool does. It does not, however, distinguish itself from the sibling attachments.upload, which an agent could easily confuse with it.

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?

"When the user shares a file that belongs on someone's record" gives a usable trigger condition with concrete examples (contract, receipt). There is no when-not guidance and no mention of the closest alternative (attachments.upload), so routing between the two is left to inference.

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