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

Annotations already declare a non-read-only, non-destructive, non-idempotent, closed-world write. The description adds genuinely new behavior: the file is private to the owner until shared, and content must fit within 5 MB after base64 encoding. It stops short of stating auth requirements or what happens on a name collision, which matters given idempotentHint=false.

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?

One sentence, zero filler, with the size constraint and privacy behavior front-loaded before the pointer to files_share. Nothing could be removed without losing information.

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 three-parameter upload with no output schema, the description covers what it does, the encoding, the size limit, the privacy posture, and the next step. It omits return information (e.g., a file identifier needed for later files_get or files_share calls) and collision behavior.

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 name, mime, and contentBase64 are already documented, including examples. The description's only additions are the encoding format and size ceiling, so it neither compensates for nor obscures the schema – baseline 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?

The description gives a specific verb and resource ('Store a new file in your workspace') and immediately pins down the format and size envelope (base64, up to 5 MB). It also names the sibling that follows this operation (files_share), so an agent can distinguish creating from distributing a file.

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?

Usage is clearly implied: this is the creation step, and files_share is the explicit alternative when the agent wants others to see the file. It does not, however, contrast itself with files_new_version, leaving ambiguity about which tool to pick when a file already exists.

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