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

With readOnlyHint=true already covering the safety profile, the description still adds real behavioral context beyond the annotations: results are workspace-scoped, include both directions, are sorted newest first, and are returned as a cursor page, plus the underlying API endpoint. It stops short of disclosing auth requirements, rate limits, or empty-page behavior.

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?

A single tight sentence that front-loads the resource and scope, then appends the pagination model and endpoint. No filler, nothing repeated from the schema.

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 two-parameter read-only list tool with full schema coverage and no output schema, the description covers scope, ordering, and pagination, which is what an agent needs to call it. It omits any hint about the shape of returned items and error/empty behavior, a minor gap.

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 description coverage is 100%, so both parameters (limit, starting_after) are already documented in the schema, and the description adds no syntax or semantic detail beyond echoing the cursor-page concept. Baseline 3 applies when the schema carries the parameter burden.

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 (List), resource (SMS messages), and scope (inbound + outbound, for the workspace), plus ordering (newest first) and paging model (cursor page). This is enough for an agent to distinguish it from bird_get_sms_message and bird_list_sms_templates without opening any 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?

Usage is implied by the resource scope and the pagination note, but there is no explicit when-to-use guidance, no statement of when to prefer this over sibling list tools, and no prerequisites or exclusions. Adequate but with clear gaps.

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