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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower, and the description still adds real context: it discloses assumptions (provider default pace unless emailsPerMailbox is set, 22 sending days a month) and limitations (no placement or reply guarantees, revenue follows only from supplied rates, nothing is ordered).

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 purpose is front-loaded in the first clause, followed by inputs, the optional revenue extension, and the assumption/limitation caveats. It is dense but each sentence carries information; minor redundancy in restating the input list.

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 an 11-parameter read-only estimator with no output schema, the description covers the input model, the optional revenue path, and the modeling assumptions. It could say more about the shape of the returned figures (inbox/domain counts, cost breakdown), but the key planning caveats are present.

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% and each parameter already carries a default-aware description, so the schema does the heavy lifting. The description mostly re-enumerates inputs (esp, prewarmed, billing cycle, per-inbox and per-domain rates) rather than adding new meaning, which fits the baseline 3 for high coverage.

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 states a specific verb and resource: it estimates how many inboxes and domains a given daily volume needs, plus the monthly cost. It implicitly separates itself from ordering tools by stating it 'orders nothing', though it never names a sibling such as quote_inboxes or plan_from_list directly.

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 only implied through the input list and the note that supplying dealValue unlocks the revenue/ROI projection. There is no explicit when-to-use framing and no named alternative for related tasks (quote_inboxes, plan_from_list, plan_rotation), leaving the agent to infer the boundary.

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