estimate_cost

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

Annotations already declare readOnlyHint and openWorldHint. The description adds value beyond them by disclosing that no AWS credentials are required—a meaningful behavioral trait—and by flagging that the estimate depends on interacting variables such as the SES pricing plan, which aligns with the open-world hint. It does not contradict 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?

Two sentences with no filler. The first sentence front-loads the action and components; the second explains why it should be used and the credentials constraint. Every clause earns its place.

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 tool with 8 parameters eliminates no output schema, the description is fairly complete: it conveys what the result represents (itemized monthly cost) and alerts the caller to input dependencies. The main minor gap is that it does not describe the exact return format or units, but the term 'cost' plus 'itemized AWS bill' gives a sufficient general picture.

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 the baseline of 3 applies. The description groups parameters into cost buckets (Wraps fee, tracked-event overage, AWS bill) and references the sesPlan dependency, but does not add per-parameter details beyond what the schema already documents.

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: 'Estimate the monthly cost of sending email with Wraps + AWS.' It enumerates what the estimate covers (platform fee, tracked-event overage, itemized AWS bill across named services), which precisely defines the tool's scope. It is clearly distinct from the sibling tools, all of which concern sending or inspecting emails, not cost projection.

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 provides explicit 'when to use' guidance: 'Use this instead of calculating by hand' and explains why (the cost model has several interacting variables). It also states a key prerequisite/constraint, 'Requires no AWS credentials.' It does not name alternative tools, but no sibling overlaps with cost estimation, so this is clear enough context.

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