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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so safety is covered. The description adds genuinely new behavior beyond that: it exposes the visibility guarantee (recent writes always visible because ranking is bypassed) and enumerates the per-entry fields, which matters because no output schema exists.

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?

Three sentences, front-loaded with the what and the when, with no filler. The trailing field-enumeration sentence is list-like but earns its place by standing in for the missing output 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?

With no output schema, the description carries the return-shape burden and does so by naming the entry fields and the ordering guarantee; pagination is handled by the since_seq schema description. An agent has enough to call it correctly, though it never states a default or cost of a large limit.

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% — limit and since_seq are fully documented in the schema, including defaults, max, and pagination semantics. The description adds no parameter-level detail of its own, so the baseline 3 applies.

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 specific verb+resource (return recent fact operations) with scope (across all agents in this tenant) and ordering (newest first). It also distinguishes itself from the sibling index_search by noting it bypasses semantic search ranking, so an agent can route between the two without opening either schema.

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?

Gives an explicit trigger — 'Use this on session start to see what other agents wrote since you were last active' — which tells the agent exactly when this tool is the right pick over search_facts/search_context. It stops short of naming alternative tools or stating when not to use it, so it falls just short of a 5.

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