Download a media item

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

Annotations already carry the safety profile (idempotentHint=true, destructiveHint=false, openWorldHint=true), and the description adds a genuinely behavioral detail beyond those hints: the operation relies on the logged-in browser session, signaling an authenticated-session dependency rather than an API-key path. No contradiction with readOnlyHint=false since downloading writes a file to output_dir.

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?

Two sentences with zero filler. The action, scope, and mechanism are front-loaded in sentence one; sentence two contributes only the ID provenance. Every word 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?

The output schema documents return values and annotations cover idempotency and destructiveness, so the description doesn't need to repeat those. Its real gap is the required output_dir parameter — completely unexplained — plus unstated file-extension and overwrite behavior. For a 3-parameter tool that is a meaningful omission, though the workflow context is otherwise sufficient.

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 67%: media_id and filename are documented in the schema, and the description reinforces media_id provenance by noting the item type and source tools. However, the required output_dir parameter has no description in either the schema or the tool description — the agent is left guessing whether it is a directory path or full path and whether it gets created. The description partially compensates for the coverage gap but not fully.

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 opens with a specific verb and resource — 'Download one Flow media item (video or image) by its media id' — making the operation unambiguous and scoped. The second sentence grounds the identifier ('Ids come from the generation and scene tools or from flow_project_open'), positioning this tool as the retrieval step alongside generation/scene siblings. It stops short of explicitly contrasting with a similar sibling, but the verb alone separates it cleanly from generate/screenshot/inspect tools.

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 description provides clear usage context: the 'logged-in browser session' clause implies a flow_connect prerequisite, and the ID-provenance sentence tells the agent this tool is used downstream of generation/scene tools. However, it never explicitly states when not to use it or names an alternative path, so it lacks exclusions and stays below a 5.

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