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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds genuine behavioral context by revealing the tool is incremental and cursor-like ('since you last asked'), implying server-tracked state. However, it does not disclose first-call behavior, result ordering, or size limits, so it remains at a minimum-viable 3.

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 compact sentence with no filler, and the differentiating frame ('since you last asked') is front-loaded before the content categories.

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 no-argument, read-only digest with no output schema, the description covers the content categories an agent needs to know it will receive. It is nearly complete, only missing first-call/return-shape expectations, which are minor given the tool's simplicity.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-parameter tool is 4.

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?

States a concrete resource and scope: an activity digest of 'what happened around you,' enumerated as speech, arrivals, departures, trips, and things others built. That verb+resource is clear, and the 'since you last asked' framing implicitly distinguishes it from siblings like look, which report current state. It lacks an explicit sibling callout, so it stops short of a 5.

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 'since you last asked' implies a polling/digest use case, so an agent can infer when this is appropriate, but no alternatives are named and no exclusions are stated. Usage is implied rather than directed.

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