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

Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context: the 96 KiB decoded size ceiling, the warning that public buckets expose uploaded files, and the access/credential model. It does not explain upsert overwrite behavior, which is a relevant mutation trait.

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 compact sentences with the size constraint front-loaded, which is good. The closing clause ('enter the Storage project key privately for this exact operation') is cryptic and reads as instructions to the operator rather than the agent, diluting an otherwise tight description.

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 output schema and 12 undocumented parameters, the description covers the essentials an agent needs to avoid harm (size limit, public exposure, auth). It still leaves key call-shaping details (upsert semantics, path conventions, the many auxiliary parameters) unexplained.

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 0% across 12 parameters, so the description must carry the load, and it does not. It never explains project_ref, bucket_id, object_path, content_base64 encoding, the upsert flag, or any of the beon_* / approval_id parameters. The size note loosely maps to content_base64 but adds no real per-parameter meaning.

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+resource (upload a storage object) and even scopes the artifact type and size ('small non-secret artifact, up to 96 KiB decoded'). It does not differentiate itself from adjacent siblings like supabase_move_storage_object or supabase_delete_storage_objects, but the verb is unambiguous.

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?

There is an implied 'when-not' via 'non-secret artifact' (don't use for secrets) and an auth note about Management OAuth and the Storage project key. However, no alternative tool is named and no explicit trigger conditions for choosing upload vs. other storage operations are given.

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