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

Annotations (readOnlyHint=false, idempotentHint=false, openWorldHint=false) only mark this as a non-read, non-idempotent write; the description adds substantial context the annotations cannot: per-type size caps, a 28 MB transport request cap, the two distinct upload hosts, a caution that platform-mediated clients may not have reachable egress, and the required follow-up confirm step.

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 the core purpose and the video/20 MB trigger before any of the branching fallbacks. It is long and ALL-CAPS-heavy, but the length is driven by real branch complexity (two hosts, chunked recipe, egress probe, three fallbacks), so most sentences earn their 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?

Despite no output schema, it names the return values (proxy_upload_url, upload_url, media_id), explains how to use each, and closes the loop through popcraft_media_confirm and medias[].value for the generate tools. An agent has everything needed to call it and act on the result.

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 100%, so the baseline is 3, but the description adds a semantic not in the schema: the 28 MB per-request transport cap that forces chunked uploads above it, which directly affects how size_bytes should be interpreted. It otherwise largely restates the caps already documented per-parameter.

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 (get upload URLs for a local file that has no public URL) and explicitly names the siblings it is not (popcraft_media_import_url, popcraft_media_upload_inline, popcraft_media_upload_widget). An agent can pick it apart from its nearest neighbors 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?

Gives explicit when-to-use conditions (local file with no public URL, video, files over 20 MB), when-not (import_url when a shareable link exists, inline only for small files, widget when client renders widgets), plus an egress-probe prerequisite and a fallback chain. Nothing is left to inference.

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