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

Annotations mark this as a non-readonly, non-idempotent, non-destructive, closed-world mutation, and the description substantially enriches that: it discloses the two-step reserve-then-PUT protocol, the short-lived uploadUrl with expiresAt, the ~5 GB per-PUT cap, the HTTPS PUT requirement, and the async follow-on via list_media polling or create_webhook. This is exactly the extra behavioral context annotations alone cannot carry.

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?

The routing decision and the two-step protocol are front-loaded, and each sentence does work (purpose, steps, async follow-on). It is dense and slightly long, but there is no filler or redundancy.

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?

Despite an output schema existing, the description helpfully narrates the return shape ({ id, uploadUrl, expiresAt }) and the required follow-up call, and it fully covers the async processing path for a fairly complex multi-step mutation. Nothing an agent needs to invoke it correctly is 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 coverage is 100% (baseline 3), but the description adds genuine value beyond it: it enumerates the body fields (filename, contentType allowed enum, size in bytes) and clarifies the ~5 GB per-PUT transfer limit that differs from the schema's 10 GiB total-size maximum. It stops short of documenting the optional projectId, so not a full 5.

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+resource (ingest a LOCAL file / create upload) and immediately distinguishes itself from the sibling import_media by the condition that selects each. An agent can tell this apart from import_media, prepare_media, and finalize_upload 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?

Explicitly states when to use this tool ('no public URL to hand import_media') and when not ('prefer import_media whenever the bytes already sit at an https URL'). It also names the mandatory follow-up (finalize_upload) and downstream consumers, leaving nothing to inference.

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