Brief: where you are and what not to touch

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

Annotations already declare this a safe, read-only, closed-world, non-destructive operation, so the safety profile is covered without the description. The description adds content scope (what categories of state come back) but says nothing about freshness, cost, caching, or result format — and with no output schema, the shape of the return is left unstated. 'Avoid redundant fetches' hints at cost but never quantifies it.

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 tight sentences with no filler: content scope first, usage condition second. It is telegraphic to the point of being a fragment ('Current focus/lineage, parked work and reasons...'), which costs a little readability but nothing is wasted.

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 zero-parameter, read-only context tool with no output schema, the description carries the main burden and does so by enumerating the returned content categories plus the trigger condition. What is missing is the response format or ordering and any sense of freshness, but for a simple briefing call the definition is sufficient 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. Schema coverage is 100% trivially, and the description correctly implies no arguments are needed.

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 names the specific payload of the brief — current focus/lineage, parked work and reasons, governing decisions, latest safe point/next step — which is concrete enough that an agent knows exactly what it gets back, distinct from a bare search (vivac_find) or explanation (vivac_why). The verb is omitted (it reads as a noun list rather than 'returns X'), and no sibling is named explicitly, so differentiation is implied rather than stated.

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?

'Use if opening context is missing/unverified or state changed' gives an explicit trigger condition, and 'avoid redundant fetches' supplies the when-not, which is unusually direct usage guidance. The gap is that it never names the alternative to call instead when the condition does not hold (e.g. vivac_find, vivac_open), leaving routing to inference.

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