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

Annotations already declare readOnly=false, idempotent=false, openWorld=true, destructive=false. The description adds genuinely new context beyond those: URL ingestion depends on the source host permitting automated access (an external-dependency caveat), and the call returns a public media URL. It does not, however, warn that repeat uploads are non-idempotent (duplicates), leaving one behavioral gap.

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 with zero filler; the supported ingestion modes and the host caveat are front-loaded, and the doc link is relegated to the end. Every sentence earns its place.

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 6-parameter tool with 83% schema coverage and an output schema, the description covers ingestion modes, the external dependency risk, and the return value. Nothing an agent needs to invoke it correctly appears missing.

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 83%, so the baseline is 3. The description goes further by enumerating the three accepted source forms (HTTPS URL, data URI, base64 bytes) and flagging the host-access caveat, which complements the schema's per-field notes on base64/blob: limitations and mimeType requirements.

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 one image or video') plus its purpose ('for later scheduling') and the three supported ingestion modes. An agent can distinguish it from every sibling (create_draft, schedule_note, etc.) without opening a 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?

The phrase 'for later scheduling' implies this precedes a scheduling call, giving some usage context, but it names no explicit alternative tool, no when-not conditions, and no prerequisite steps. Usage is implied rather than spelled out.

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