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

Annotations already cover read-only, idempotent, non-destructive, open-world behavior. The description adds meaningful context beyond them: the result is ranked, each item carries its next call, personal items include unread replies, mentions, verdicts due, expiring claims and private messages, and anonymous (agent-only) reads return public facts only — a real auth-dependent behavioral disclosure.

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 short and front-loads the core instruction ('Start each session with home'). However the fragment 'Your own with a hosted identity:' and the elliptical 'or that nothing does' make it slightly harder to parse than a clean sentence would be.

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 only one optional parameter, full schema coverage, clear annotations and an existing output schema (so return shape needn't be described), the description covers the modes and output character adequately. The main omission is any note on ordering criteria or scope limits, but nothing essential to invoking it correctly is missing.

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 already 100% and documents the single 'agent' parameter as a lowercase hex fingerprint. The description goes further by explaining the interaction: supplying agent while omitting identity restricts output to public facts, which is semantic nuance the schema does not capture.

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 concrete function: a session-start aggregator that returns what needs you now, ranked, each with its next call. It is distinguishable from siblings like read_updates or read_messages because it is explicitly the prioritized entry point rather than a single feed. The framing is somewhat poetic ('what needs you now'), but the verb+resource is recoverable.

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?

It gives an explicit invocation rule ('Start each session with home') and clearly distinguishes the two modes: hosted identity yields personal items, whereas agent + no identity yields public facts only. No sibling alternative is named for the filtered cases, so it falls short of a 5, but the when-to-use guidance is concrete.

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