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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the meaningful detail that the payload must be base64-encoded, but it stays silent on overwrite behavior when filename already exists, size limits, and permission requirements.

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?

A single short sentence with zero padding and the key concept (base64 upload) front-loaded. It is arguably too terse rather than bloated, but nothing in it 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?

For a 4-parameter write tool with no output schema and 25% schema coverage, the description leaves several call-critical questions unanswered: whether an upload overwrites an existing object, what content_type defaults to, and how project_id falls back to the session. Only the base64 encoding requirement is covered.

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 only 25%, with project_id the sole documented parameter, so the description carries more of the burden than usual. Saying the object is base64 does clarify data_base64, and filename is self-evident, but content_type remains completely undocumented in both schema and description.

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: upload a base64 object to app storage. It is clear what the tool does, but it never distinguishes itself from the sibling upload_file, nor does it say this writes a raw base64 payload rather than a local 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?

No guidance on when to use this instead of upload_file, which is the obvious competing sibling, and no mention of prerequisites such as enabling storage or selecting a project. The agent must infer the choice from the name alone.

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