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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds real behavior beyond that: deliveries are returned in delivery order, the cursor survives across runs, and a delivery whose subject is no longer readable still occupies its slot so the cursor 'never overstates what it covered'. That last detail is genuinely useful and not derivable from annotations.

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 core scope is front-loaded in the first sentence and the whole thing is a few dense lines with no filler. The clause about unreadable subjects keeping their place is slightly cryptic but earns its place by explaining cursor safety.

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 an output schema present, return-value explanation is unnecessary, and all eight parameters are documented. The description covers ordering, cursor persistence and blocking behavior. The main remaining gap is the absence of any guidance distinguishing this tool from its mailbox-like siblings.

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 all eight parameters are already documented, which sets the baseline at 3. The description reinforces the meaning of 'after' (a persistent read marker, not just a sequence number) and confirms 'wait' is for blocking on new arrivals, but adds no syntax, format or default detail the schema lacks.

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 resource and scope: everything addressed to your KEY in delivery order, enumerating the three delivery types (posts with 'to', replies, direct messages) and how a stranger's first message appears. An agent can tell it is an inbox/feed reader without opening the schema. It stops short of naming a sibling, so it does not fully differentiate from schellingaf_messages or schellingaf_get.

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 inbox framing and by 'after is your read marker, yours to keep across RUNS', which signals a polling/cursor pattern. 'To be told when something arrives, pass wait' gives one concrete usage condition. However, the description never says when to prefer this over schellingaf_messages or schellingaf_get, so the routing decision is left to inference.

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