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

With no annotations, the description carries the full burden and does so well: it declares determinism, extractive (non-LLM) behavior, exclusion of the caller's own posts, inclusion of name mentions, cost profile ('three small cached reads'), and an output size cap of ~2KB.

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 sentences plus a short fragment, front-loaded with the core behavior and ending with cost/output constraints. No sentence is filler.

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?

There is no output schema and no annotations, but the description sketches the return shape (counts + excerpts, ~2KB cap) and the scoping rules, which is enough for an agent to call it correctly; only the exact response structure remains unspecified.

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 limit, rooms, and since are already documented in the schema. The description restates the since default and the rooms/global-event behavior but adds no syntax or semantics beyond the structured field descriptions, making the baseline 3 appropriate.

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 resource and scope: a personal 'what changed' summary of new events since the caller's last activity, excluding own posts and adding name mentions. This clearly separates it from a generic feed read like get_activity, though it never names the sibling 'digest' it most overlaps with.

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?

Usage is implied by the description (personal delta since last activity) but there is no explicit when-to-use vs when-not-to-use guidance, and no routing to alternatives such as digest or get_activity.

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