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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is lower; the description still adds real context: default filtering semantics, cursor pagination keyed on fired_at, and the Sample-tier rejection with the sp500+ requirement. It does not mention ordering side effects or whether marking read is implied, but the important behavioral facts are covered.

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?

One tight paragraph, front-loaded with the core purpose, then scope, then defaults, then pagination and tier constraints. Dense with parentheses but no sentence is filler; slight compression could improve readability of the item-type enumeration.

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, full schema coverage, and safety annotations, the description only needs to add scope, filtering defaults, and access constraints — all present. The tier restriction is a particularly valuable addition an agent could not infer from structured fields.

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 earns extra by explaining the effective defaults in prose ('dismissed items are hidden and read items are included'), which makes include_dismissed and unread_only interpretable at a glance. It also confirms the cursor is keyed to fired_at, matching the cursor parameter semantics.

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?

States a specific verb and resource (listing the caller's in-app inbox) with ordering ('newest-first'), and enumerates what the items actually are (signal FIRES on the dashboard channel, platform notifications from the edge-gateway). It explicitly contrasts with list_signals, so an agent can distinguish the two without opening either schema.

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?

Clearly routes signal-definition lookups to list_signals, which is the nearest sibling. It also implies when defaults apply (dismissed hidden, read included), but gives no guidance on choosing limit values or when to paginate versus restart.

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