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

Annotations already declare a non-destructive, idempotent write, and the description adds real context beyond them: nothing is published, one media_id is returned per file in the same order (no output schema exists, so this is essential), the call consumes the storage quota, and operation_id must be preserved on retry. This is well past what the annotations alone convey.

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?

Front-loaded with purpose, then return contract, then input constraint, then fallback, then quota/retry notes. Each sentence carries a distinct operational fact; nothing is repeated from the schema or annotations.

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 only 50% schema coverage, the description supplies the missing return contract, the input-validity rule, quota implications, retry/idempotency behavior, and the escalation path. An agent can call this correctly without further information.

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 50% — operation_id is documented in-schema but the files array items have no descriptions. The description compensates by constraining what a valid file reference is (conversation attachment only, not a filesystem path or filename) and by explaining the order guarantee of the returned ids. It does not clarify the roles of file_id vs download_url vs mime_type, which remains a small gap.

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 (receives 1-10 files and saves them to the brand) plus the exact scope constraint 'sin publicar nada' and the supported types/sizes. It is immediately distinguishable from publish_post or create_upload_link.

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?

Gives explicit when-to-use (files attached or generated in the conversation) and when-not (paths like /mnt/data or plain filenames do not work), and names the fallback sibling create_upload_link for the case where the file cannot be passed here. It also routes the agent forward to create_post / create_and_publish_post for consumption of the returned media_id.

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