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

Annotations already declare readOnly, idempotent and non-destructive behavior, so the bar is lower. The description adds genuinely new context by naming the required scopes ('companies.read and contacts.read') and the underlying endpoint, which an agent cannot get from the annotations or 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?

A single compact sentence with the resource and scope front-loaded, followed by the permission requirements. No filler. It could drop the raw endpoint path without losing meaning, which keeps it from a 5.

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 list tool with no output schema and fully documented parameters, the description covers purpose, scope and permissions. The main remaining gap is return shape and pagination behavior, which the schema partly handles for offset but not for the response.

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 the offset parameter is documented in unusual depth in the schema itself, including how to feed the cursor back. The description adds nothing beyond what the schema provides, so the baseline 3 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?

States a specific verb and resource ('List the contacts') plus a clear scope ('linked to one company'), which implicitly distinguishes it from sellsy_list_contacts and sellsy_search_contacts. No sibling is named explicitly, so it is clear but stops short of full differentiation.

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 scope 'linked to one company' implies when this tool is appropriate versus listing all contacts or searching, but the description never states the condition explicitly or names an alternative. Usage must be inferred from the scope phrase.

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