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

Annotations already declare readOnlyHint=true, so the description's statement 'View sent ... history' aligns and adds minor context about the scope (sent messages, audit use). No additional behavioral details like pagination, rate limits, or data freshness are provided, but given the annotation coverage, the description suffices without contradicting the annotations.

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 two sentences, starting with the main action and followed by filtering options and use case. It is concise but contains an inaccurate claim ('delivery status') that could have been avoided. Still, it is front-loaded and generally 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 a simple read-only list tool with 100% schema coverage and an output schema, the description covers the essential purpose and suggests a use case. However, the incorrect claim about delivery status undermines completeness. The description could be improved by accurately listing filterable parameters and noting defaults like limit=50.

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 100% coverage, so the baseline is 3. However, the description adds 'Filter by ... delivery status' which is not a parameter in the schema, creating confusion. It does not provide any meaningful details beyond the schema for the actual parameters (type, limit, channel). The description misleads about available filtering options, reducing its value.

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 'View sent SMS and email message history', specifying the verb (view) and resource (history of sent messages). It also mentions filtering options, distinguishing it from sibling tools comms.send_email and comms.send_sms which are for sending, not viewing.

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 indicates the tool is useful for auditing communications and describes filtering by channel, message type, or delivery status. However, it does not provide explicit when-not-to-use or alternative tools, and the claim about 'delivery status' is misleading because the input schema does not include a delivery_status parameter. This omission impacts clarity on when to use this tool effectively.

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