update_library_streams_by_stream_id_ext

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

Annotations already indicate this is a non-read-only, idempotent, non-destructive operation. The description adds useful context by stating offset is in milliseconds and that ext is not actually part of the endpoint despite being required. It doesn't contradict the annotations, but it doesn't explain side effects or what changing the offset does to the stream.

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 description is short, well-organized, and front-loaded with the core action. The parameter list is compact and each line adds necessary information. There is no redundant filler.

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 tool has a simple shape, an output schema, and annotations that provide safety-related context. The description covers parameter meanings and the ext quirk, but it lacks clarification on what a null offset means and doesn't distinguish this tool from similar playback-offset operations. It is minimally sufficient for calling the endpoint but leaves semantic gaps.

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?

The schema has 0% description coverage, but the description compensates by explaining all three parameters: stream_id identifies the stream, ext is a required placeholder, and offset is in ms. The ext clarification is especially valuable because it prevents an agent from misusing a required but meaningless 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?

The description states a clear verb and resource: "Set a stream offset." This distinguishes it from the sibling get_ and delete_ operations on the same path. However, it doesn't elaborate on what a stream offset means or how it relates to playback, so it's clear but not fully differentiated.

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?

There is no guidance about when to use this tool versus alternatives like create_player_playback_set_view_offset or get_library_streams_by_stream_id_ext. The description just repeats the action without providing context, use cases, or exclusions.

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