list_feed

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses the output format (standard YouTube watch URLs) and the default scope (all subscribed channels), which is useful. However, it doesn't mention auth requirements, ordering guarantees, pagination, or potential errors, leaving a moderate transparency 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?

Two concise sentences, front-loaded with purpose, then output format. Every phrase earns its place, and there is no redundant content or 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?

For a simple optional-parameter list tool with no output schema, the description provides the essential return format and scope, plus a hint about downstream use. It could mention ordering/pagination, but 'most recent' implies ordering and the URL output is the key return detail. This is slightly above minimum viable.

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 input schema covers all three parameters (limit, channelId, sinceDays) with descriptions at 100% coverage. The description adds no additional parameter semantics beyond saying the feed is 'across all subscribed channels,' which overlaps with the schema. Baseline 3 is appropriate since the schema does the heavy lifting.

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 uses a specific verb ('List') with a clear resource scope ('most recent uploads across all subscribed channels') and clarifies it's the subscription feed. This strongly distinguishes it from sibling tools like list_channel_uploads (single channel) and list_subscriptions (list of channels).

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 'across all subscribed channels' and 'subscription feed' establishes when this tool is appropriate versus a single-channel listing tool. It doesn't explicitly name alternatives or state exclusions, but the context is clear enough for an agent to decide between list_feed and list_channel_uploads.

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