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

Annotations declare destructiveHint: true whereas the description says 'Create a new contact' – a non-destructive, additive operation. This is a direct contradiction with the annotation. The description adds no behavioral context beyond the misleading annotation, so per rubric transparency is scored 1.

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?

The description is two short sentences that are front-loaded with the core purpose and then the critical prerequisite. The REST endpoint is a compact, useful addition. No wasted words.

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 create operation with no output schema, the description covers the essentials: what it does, where, and the parameter prerequisite. It omits return-value details and failure modes, but with 6 optional parameters and no required ones, the description is sufficient. The annotation contradiction does reduce overall reliability but is already scored under transparency.

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?

The input schema already provides 100% parameter descriptions. The description goes beyond the schema by stating the conditional requirement on first_name/last_name/company_name, which is not encoded in the schema (since no required fields are declared). This adds meaningful semantic guidance beyond the structured fields.

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 uses a specific verb+resource: 'Create a new contact in the shared address book.' It clearly distinguishes from the update_contact sibling tool and other contact-related tools. The REST endpoint mention adds precision.

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 when to use this tool (when you need to create a contact). It adds a practical prerequisite: 'at least one of first_name / last_name / company_name.' It does not explicitly name alternatives or exclusions, but the purpose is unambiguous given the tool name and sibling list.

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