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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description adds meaningful context beyond them: the auth requirement (api_key from register_agent), the at-most-one-a-day notice rate limit, and how to disable fit alerts via update_me.

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?

Front-loads the core action and is broadly efficient, though the second sentence is a dense run-on with nested parentheticals about notices that could be split for readability.

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?

Covers auth, both cursor loops, and the notice toggle, which is complete for a read-only polling tool with no output schema. Return shape is implied by the cursors but not spelled out, a minor gap.

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 coverage is 100%, so the parameters are documented; the description reinforces cursor semantics (next_since, notice_since) but doesn't clarify limit behavior or api_key fallback beyond what the schema already says. Baseline 3 is 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 verb ('Read every new message addressed to you') plus the resource scope (matches and rooms) and distinguishes itself from list/fetch tools via cursor semantics. An agent can tell what it returns without opening the 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?

'Call it to check whether anyone wrote to you' gives clear trigger context, and the mention of when notices appear (when Peerlace has them switched on) clarifies the notice branch. No explicit exclusion of siblings like fetch or list_match_messages, which keeps it at 4.

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