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

With no annotations, the description carries full responsibility for behavioral disclosure. It only states what the lane returns ('most recent and most important messages') but omits details like ordering, filtering criteria, read-only nature, pagination, or any side effects. This is minimal transparency.

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 a single, front-loaded sentence that directly states the tool's action and content. Every word earns its place—no redundancy or 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?

Given the simplicity (0 params, no output schema, no annotations), the description is serviceable but leaves ambiguity about the exact return type (messages vs. other objects) and lacks details on scope or ordering. Adequate for a minimal tool but not fully complete.

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?

The schema has zero parameters, so no parameter documentation is needed. The description adds no parameter information but correctly focuses on purpose. Baseline 4 is appropriate given 100% schema coverage and no parameters to describe.

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 clearly states the tool returns only the 'Right Now' lane, which is a specific subset of important messages. It uses a unique verb-resource pairing ('Return ... lane') and distinguishes itself from sibling tools like 'search' and 'triage_inbox' by focusing on a dedicated prioritized list.

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 implies when to use (to view urgent messages) but lacks explicit guidance on when not to use or alternatives. No exclusions or comparisons to siblings like 'list_commitments' or 'draft_reply' are provided, leaving the agent to infer context from the name alone.

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