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

With no annotations present, the description carries the behavioral burden and it does disclose that the call is read-only, which is the key behavioral trait. It also clarifies the semantic meaning of the returned numbers (included + purchased extras and estimated throughput), going beyond a simple 'returns capacity.' It does not mention auth/rate-limit concerns, but those are standard and not critical for this read-only getter.

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 a single sentence that front-loads the core meaning and appends 'Read-only' as a crisp safety signal. Every phrase earns its place; there is no fluff or repetition of the tool name.

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 zero-input, read-only tool the description conveys the two essential result concepts and marks the operation as safe. It is not a 5 because there is no output schema and the exact return shape/field names are not described, so an agent cannot predict the response structure beyond the high-level values.

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 tool has zero parameters and 100% schema description coverage, so the baseline is 4; there are no parameter semantics for the description to clarify. The description appropriately focuses on the returned data instead.

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 precisely identifies the resource (SDR sender email addresses/capacity) and the two data points returned (included + purchased extras, estimated daily throughput). It clearly differentiates from sibling getters like get_agent_plan_limits or get_subscription_limits by naming the specific SDR capacity concept.

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 implies consumption as a capacity lookup for the account's SDR email sending, but it never explicitly states when an agent should choose this tool over sibling tools or when not to use it. For a zero-parameter read-only getter the implication is enough to avoid severe errors, but it lacks explicit alternative routing.

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