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

The description goes well beyond the readOnly/idempotent/destructive annotations by detailing item composition (signal FIRES with dashboard channel + platform notifications), ordering (newest-first, cursor-paginated by fired_at), default visibility (dismissed hidden, read included), and tier restriction. This gives substantial behavioral context not carried by annotations alone.

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?

Four dense sentences with zero fluff, front-loaded with the core purpose then layered specifics. Every sentence carries distinct value: scope, item composition, sibling routing, defaults, pagination, and access tier. Highly efficient.

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?

For an annotated read-only list tool with an output schema, the description provides everything needed to call it correctly: resource scope, item types, ordering, pagination behavior, default filters, and access restrictions. No significant gap remains.

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 baseline is 3; the description adds meaning by connecting the cursor param to pagination by fired_at and explaining default item visibility which maps to unread_only/include_dismissed. However, it doesn't add unique meaning to the limit parameter since the schema already documents it.

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 opens with a specific verb and resource ('listing of the caller's in-app inbox') and immediately distinguishes itself from list_signals by explicit note: 'use list_signals instead for the signal definitions themselves.' It also clarifies what type of items are in scope, so an agent can identify this tool unambiguously among siblings.

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?

Explicitly states the alternative tool (list_signals) and the condition that routes to it (need signal definitions vs inbox items). Also documents access constraint ('Sample tier rejected — signals are a paid-tier feature') and default filtering behavior, giving clear when-to-use/when-not-to-use guidance.

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