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

Annotations already declare readOnly/destructive=false/openWorld. The description adds non-obvious context: the full set of possible ei_status outcomes, the downstream call for discarded invoices, and the auth prerequisite (Cotlet API key with app access). It stops short of describing error/failure 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?

Front-loaded with purpose, then the status enumeration and follow-up rule; every block earns its place because the enum values are not in the schema. Minor redundancy between 'Read the SDI status' and 'Returns the ei_status of the invoice.'

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?

With no output schema and no schema enums, the description carries the return-value burden by listing all ei_status values inline, names the follow-up tool, and states the auth requirement — everything an agent needs to call and interpret this 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% — both company_id and invoice_id are documented, including that invoice_id comes from list_invoices/create_invoice. The description adds no parameter-level detail beyond that, 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 ('Read the SDI status of an invoice') and pins down the exact field returned ('ei_status'). This clearly distinguishes it from siblings like get_invoice, verify_einvoice, and send_einvoice without needing 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 an explicit conditional next step: 'For discarded invoices, follow with get_einvoice_rejection_reason,' which routes the agent to a specific sibling. It does not, however, say when to use this versus verify_einvoice or how it fits after send_einvoice, so guidance is strong but not exhaustive.

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