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

Annotations already cover safety (readOnly, non-destructive, openWorld), so the description's job is lighter. It adds useful behavior: the returned fields (invoice no, document/due date, days overdue, dunning level, amount, paid, outstanding) and the optional as-of key date, which tells the agent what results look like without an output schema.

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 dense sentences with the core purpose front-loaded, followed by the field list and the optional key-date note. No filler.

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, the description helpfully enumerates the returned fields and clarifies the customer/vendor split and default. Pagination is left to the schema, which is fine given its 100% coverage; a note on when to use this vs list_invoices would make it complete.

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 parameters are already documented with defaults and constraints. The description only restates 'customers ... default' and 'optionally as of a key date,' adding no syntax or semantics beyond the schema—baseline 3.

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 ('Open items (unpaid invoices)') and names the underlying record type (OPEN_ITEMS_GET), and clarifies the scope as receivables (default) or payables. It also disambiguates from collmex_list_invoices by defining the items as *unpaid* invoices.

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 implied usage via 'for customers (receivables, default) or vendors (payables)' and 'Optionally as of a key date,' but never says when to prefer this over collmex_list_invoices or collmex_list_accounting_documents, nor any prerequisites.

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