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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the safety profile is supplied. The description adds the substantive side effects beyond the annotations: it creates/links a contact record plus a lead entry in the lead inbox, and works across any thread type. It omits the duplicate-creation risk implied by idempotentHint=false, keeping it from a 5.

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 definition is front-loaded with the core action before the 'When to use' list, and every sentence carries information (trigger, counter-example, follow-up). The bullets keep it scannable despite covering several scenarios, with no filler.

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 annotations covering the mutation profile and no output schema required, the description is nearly complete for a capture tool: it explains the trigger, what is created, and cross-field requirements. The only meaningful gap is that it does not describe what the call returns or how duplicates are handled (relevant given idempotentHint=false).

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 each field is already documented, making 3 the baseline. The description still adds cross-parameter meaning the per-field schema does not: at least one of name/phone/email suffices, name can be omitted, and company/use_case are optional context. That is genuine semantic value above 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 first line gives a specific verb and resource: 'Save the current contact's details as a structured lead (contact + Contacts tab),' and later clarifies it 'Creates/links a contact record and a lead entry in the workspace's lead inbox.' The purpose is unambiguous, but it never explicitly contrasts itself with the many contacts_* siblings (contacts_update, contacts_find, contacts_merge), so it earns a 4 rather than a 5.

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?

A dedicated 'When to use' block states the triggering context (website-chat or voice-call conversation, as soon as one identifier is given) with concrete examples (booking a demo/class) and even handles the edge case 'a phone number with no name is still a lead.' It stops short of naming when NOT to use it or pointing to a relevant alternative like contacts_update, so it is strong but not exhaustive.

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