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

readOnlyHint=true already establishes the safe read profile, so the bar is lower. The description still adds real behavior beyond the annotation: AND-combined filters, case-insensitive substring matching with a 3-character minimum, wildcard characters, and the next_page-to-page pagination handoff.

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 dense sentences, front-loaded with what the tool returns and how filtering works, ending with the endpoint. No filler or redundancy.

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 7-parameter read-only list with no output schema, the description covers filtering, matching rules, and pagination adequately. It does not describe the shape of a returned contact, but with readOnly annotations and thorough schema docs this is a minor gap.

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 baseline is 3 and the schema already carries per-parameter meaning. The description adds value by explaining that filters are AND-combined and that name/email match as case-insensitive substrings with wildcard support, semantics not restated in 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?

Specific verb ('List') plus resource ('customers and vendors' / contacts) and scope ('optionally filtered'). It is clearly a list/search operation, distinguishable in spirit from lexware_get_contact, but it never explicitly contrasts the single-fetch sibling, so full sibling differentiation is missing.

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 conveys how to use filters ('filters combine with AND') and the paging convention, which is implied usage. However it never states when to prefer this over lexware_get_contact or lexware_create_contact, and offers no exclusions or prerequisites.

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