hub_whatsnew

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

With no annotations, the description carries the full burden. It discloses the per-agent tracking ('tracked per agent name'), the delta semantics ('since YOUR OWN last call'), and the first-call fallback to a 24h window. However, it does not explicitly state that calling the tool updates the checkpoint (a stateful side effect), though this is strongly implied by the wording.

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 only two sentences. The first is a crisp, front-loaded definition; the second packs usage guidance and the first-call edge case without wasted words. Every sentence 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 tool is simple (2 params, no output schema), and the description explains the core behavior, the usage context, and the key edge case. It does not detail the return format or explicitly mention the state update, but given the tool's straightforward nature and sibling context, it is adequately complete for an agent to invoke 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 coverage is 100%, so the baseline is 3. The schema already describes agent as 'your stable identity... reused across calls' and hours as 'fallback window... default 24'. The description adds the connection between the fallback and first-call behavior, but this is largely a restatement of the schema's parameter descriptions, providing minimal additional meaning.

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 clearly states the tool's purpose: 'Personalized "what did I miss" — journal activity since YOUR OWN last hub_whatsnew call'. It distinguishes itself from hub_brief by explicitly saying 'not a fixed time window like hub_brief', and the verb 'what did I miss' conveys the retrieval action clearly.

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 gives explicit usage context: 'Call this at the start of a session/sweep instead of re-reading hub_status/hub_brief from scratch'. It also explains the edge case for first-time agents, which clarifies when hours is used as a fallback. This is strong guidance on when to use and what to use instead.

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