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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral detail beyond that: multi-word AND semantics across fields, the VALIDATION_ERROR on empty q, and an empty list rather than an error on no match. It stops short of describing what a returned record contains beyond an id.

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?

Three short sentences, matching semantics first, then error behavior, then the next-step routing. No filler and nothing buried.

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?

No output schema exists, yet the description tells the agent what a miss returns and that results carry an id usable as customer_id, while pagination is fully documented in the schema. Only the shape of a hit's fields is left implicit.

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%, so the baseline would be 3, but the description adds meaning the schema does not: the conjunctive word-matching rule over name/TIN/BRN/email/address. The limit/cursor paging modes remain schema-only, which is acceptable.

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 (find registered buyers by text) plus the exact matching rule: every word must match one of the buyer's text fields such as name, TIN, BRN, email or address. That rule alone distinguishes it from the sibling read/list tools without opening a 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?

Covers the failure path (empty q refused with VALIDATION_ERROR), the zero-result path (empty list, then call myinvois_customer_create to register), and the forward path (myinvois_invoice_generate with the id as customer_id). Each branch names the concrete next tool.

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