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

With no annotations, the description carries the full burden. It usefully discloses that null is a normal return value and clarifies the data model. However, it does not explain what happens if neither companyId nor contactId is provided, or whether supplying both is allowed or which takes precedence.

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 concise sentences, all adding value. The core purpose is front-loaded, and the clarifications about null returns and data location are relevant and efficiently worded.

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?

The description explains what is returned and the normal null case, which is helpful given there is no output schema. However, it omits parameter decision rules and does not address the plural sibling, which an agent would need to select this tool confidently.

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 0%, so the description must compensate. It does map the parameters to entities: companyId for company and contactId for contact, but it does not clarify whether one is required, whether they are mutually exclusive, or any format expectations. Some meaning is added, but key semantics remain unclear.

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 clearly identifies the action (get), the resource (billing profile), and the target entities (contact or company), listing the fields returned. It also distinguishes billing details from a separate customers list. However, it does not explicitly differentiate itself from the similarly named sibling billing_profiles_get, which is a notable ambiguity.

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?

The description implies when to use this tool: when you need a single billing profile for a contact or company, especially since billing details hang off the contact record. But it never explicitly states when not to use it or what alternatives like billing_profiles_get are for.

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