Get contact

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the scoping detail that exactly one contact is returned and that either identifier can be used, but it does not disclose return format or error behavior. This is acceptable but not richly transparent.

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?

One clear sentence with no filler. The core lookup behavior and both identifier options are front-loaded and immediately actionable.

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 simple read-only lookup, the description plus fully annotated schema covers the essential invocation details. There is no output schema, so a brief note about the returned contact object would have been helpful, but the absence is not a major gap given the tool's simplicity.

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%; contact_id and customer_id are already documented in the schema. The description restates the distinction between the Moneybird id and the customer's own reference, which adds minor clarity, but it contributes little beyond the schema.

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 states a specific action ('Retrieve a single contact') and names the two lookup keys (Moneybird id and customer_id reference). This clearly distinguishes it from sibling tools like list_contacts, which retrieves multiple contacts.

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 clearly implies this tool is for fetching one known contact by identifier rather than for listing or searching contacts. It does not explicitly name list_contacts as the alternative for broad queries, but the single-contact framing plus identifier parameters gives adequate usage context.

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