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

The description adds context beyond the annotations: default visibility (dismissed hidden, read included), pagination by fired_at, and the fact that items come from cron evaluator or test_signal and edge-gateway. It also discloses the paid-tier restriction. Annotations declare read-only and idempotent, and the description aligns with that while adding meaningful behavioral detail.

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 dense but not excessively long. The main purpose is front-loaded in the first sentence. It efficiently conveys item composition, default behavior, pagination, and access restrictions. Slightly long but every sentence adds value, so it earns a 4.

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 tool's moderate complexity, rich annotations, and existing output schema, the description provides a complete picture: what the tool does, what items it contains, how defaults behave, pagination scheme, and tier restrictions. There is no significant missing context.

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 covers 100% of parameters with descriptions, so baseline is 3. The description adds value by explaining the default behavior (dismissed hidden, read included) which directly relates to the include_dismissed and unread_only parameters, and mentions cursor pagination via fired_at, linking the cursor parameter to a semantic field. This goes beyond the schema's individual parameter descriptions.

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 lists the caller's in-app inbox in newest-first order, specifying the item types (signal fires with dashboard channel plus platform notifications). It explicitly distinguishes from sibling list_signals by saying 'use list_signals instead for the signal definitions themselves'.

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 provides explicit usage guidance by naming the alternative tool (list_signals) for signal definitions, and also notes the sample tier rejection, informing the agent when this tool is not available. This satisfies the when/when-not criteria.

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