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

With no annotations provided, the description carries the full behavioral burden. It discloses the crucial side effect: 'Advances your last-check marker unless peek is true.' This tells the agent that a normal call is stateful and that peek provides a non-advancing read. It does not cover auth/rate-limit details, but the core side effect is explicitly surfaced.

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 two sentences and front-loaded: it opens with the core purpose, follows with a useful concrete list of update types, then gives the when-to-call and side-effect caveat. No sentence 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 tool with no output schema and no annotations, the description covers the main operational essentials: what updates are included, when to call, and how the last-check marker behaves. It does not describe the return structure or pagination, but it is otherwise sufficient for an agent to invoke it 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 description coverage is 100%, so the schema already documents all three parameters. The description adds a little contextual reinforcement, especially for peek by explaining the marker-advancing behavior, but it does not add meaningful new semantics for since or token beyond what the schema already provides.

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 states a specific purpose: retrieving everything that happened 'FOR YOU since your last check' and enumerates concrete update categories (answers, direct-discussion messages, suggestion verdicts, etc.). This clearly distinguishes check_updates from the general list_* siblings, which do not aggregate personalized-async updates.

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 an explicit usage instruction: 'Call this at the start of a session.' It does not explicitly name alternatives or when-not-to-use cases, but no sibling tool provides the same personalized update-loop behavior, so the context is sufficiently clear.

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