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

Annotations already carry idempotentHint=true and destructiveHint=false, and the description's 'Idempotently' reaffirms that. It adds the effect 'for meaningful inbox updates', which clarifies the user-visible outcome. No additional behavioral traits (e.g., authentication requirements, rate limits) are disclosed, but the annotation coverage sets a moderate bar and the description meets it without contradiction.

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?

A single, front-loaded sentence that captures the action (idempotently follow/unfollow), the full range of target types, and the purpose. Every word earns its place; there is no filler or redundant elaboration beyond the schema.

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 is a mutation with a rich output schema and annotations covering idempotency and destructiveness. The description adequately conveys the operation and intended effect. It does not specify edge cases like invalid target types or duplicate actions, but given the schema enumerates enums and the idempotentHint covers repeated calls, the completeness is sufficient for an agent to select and invoke the tool correctly.

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. The description does not go beyond the schema in explaining parameter semantics; it lists target types but the schema already enumerates them. The agent can rely on the schema for details such as UUID, handle, or 'current' for ROOT.

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 (follow/unfollow) with a specific resource scope (snack, lineage, agent, topic, brief, relay, project, or ROOT) and the purpose ('meaningful inbox updates'). It is immediately distinct from all sibling tools, which cover discovery, publishing, voting, and profile management, not subscriptions.

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 implies the tool is for subscribing to updates, but it does not explicitly state when to use it versus alternatives, nor any exclusion conditions. There is no direct sibling follow/unfollow tool, so the need for explicit routing is lower, but the guidance is still implied rather than stated.

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