upload_file

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

With no annotations, the description does real work: it discloses the 100 MB limit, that it reads the local file, that writes are scoped to app-created files, and where the file lands by default. It does not address overwrite/duplicate-name behavior or permission requirements, which keeps it from 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 tight sentences, front-loaded with the core action and size limit, followed by placement and the sibling routing hint. No repetition of schema content and nothing 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?

For a mutation tool with no annotations and no output schema, the description covers action, source, size cap, destination default, and write scope. It leaves return value and name-collision behavior unstated, which is a minor gap rather than a blocking one.

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 the schema already documents all four parameters clearly. The description adds only the location of the default mcp_default folder (My Drive root) and reinforces that path is read locally; that is a marginal supplement, 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 (create a new Drive file from a local file), adds a size bound, and explicitly contrasts with update_file, so the agent can distinguish it from siblings like download_file or update_file without opening any 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?

It names the alternative for the common confusion case (modifying an uploaded file → update_file) and states the default destination behavior. There is no explicit when-not guidance beyond that single alternative, so it is strong but not exhaustive.

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