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

Annotations only declare write/openWorld/non-destructive, but the description adds substantial context beyond them: the email goes out under the company name, cannot be recalled, supports up to four recipients, supports open-tracking for PDF links, requires per-call confirmation, and carries an auth requirement. This is exactly the behavioral richness the annotations omit.

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 load-bearing facts (irreversibility, confirmation requirement, recipient limit, tracking) are front-loaded and earn their place, but the opening two sentences restate the same action ('Email a published invoice...' / 'Sends a published invoice by email...'), which is mild redundancy.

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 3-parameter irreversible send tool with no output schema, the description covers preconditions, safety, tracking, and auth. It stops short of indicating what a successful call returns, but otherwise an agent has what it needs to invoke correctly.

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 schema already documents invoice_id, recipients, and attach_pdf. The description restates the link-vs-attachment mode and the four-recipient cap but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 and resource ('Email a published invoice to the customer'), names the platform scope, and immediately distinguishes it from sibling mutation tools like bokio_publish_invoice or bokio_create_invoice by its action (delivering an already-published invoice). An agent can tell what it does without opening the 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?

Gives clear operating context: the invoice must be published, the call reaches other people and requires user confirmation by default (removable), and it needs a Cotlet API key with access. It does not explicitly name alternative siblings (e.g., publish first), but the 'published invoice' precondition routes the agent adequately.

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