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

Beyond the readOnly/idempotent annotations it discloses genuinely non-obvious traits: ordering (newest first), the required Last Price credential, and that a self-registered sandbox key is refused with 403 until the workspace is claimed. The 403 failure mode is exactly the kind of pre-call context an agent cannot get from structured fields.

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?

Four short sentences, each carrying distinct information: scope, paging, access precondition, workspace precondition. Scope and ordering are front-loaded; nothing is padded.

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 still omits what a contact record actually contains, so an agent cannot predict the response shape. Everything else needed to call it correctly, including auth and workspace prerequisites, is covered.

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% and each parameter already has a description, so the description only restates that limit/offset page and customer_id filters. It adds no format or constraint detail (e.g. the 1000 maximum) beyond the schema, so the baseline 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?

Specific verb + resource ('List the contacts in your workspace') with ordering ('newest first') and an optional narrowing path ('only one customer's with customer_id'). It is trivially distinguishable from siblings like get_contact (single record) and list_customers (different resource).

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?

Clear conditions are given: use customer_id to scope to one customer, use limit/offset to page. It does not name an alternative tool or state when not to use it, but for an unambiguous list operation that is a minor gap.

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