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

The description contradicts the idempotentHint=true annotation: it says that without an email a new contact is always created, meaning repeated calls can create duplicates. Although it does disclose merge behavior and cost, the direct contradiction with an annotation forces a low score.

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 short, front-loaded with the core upsert purpose, and every sentence adds concrete behavior: partial update, tag addition, custom-field merge, no-email fallback, and cost. 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 12-parameter mutation tool with no output schema, it covers the essential behavior: upsert semantics, partial update rules, merge behavior, no-email behavior, and cost. It could mention the return value or give more parameter-specific guidance, but it is largely complete.

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 description coverage is only 25%, so the description must compensate. It usefully explains email’s role in upsert, tags being added, custom fields being merged, and that only sent fields change, but it leaves many parameters (name, notes, phone, title, language, location, timezone, lifecycle_stage) without added semantics.

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 clearly states it creates a contact or updates an existing one by email, using a specific verb and resource. It does not explicitly differentiate itself from sibling tools like crm_update_contact or crm_save_contacts, which keeps it from 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?

It implies the tool is for upserting a contact by email and explains the no-email case, but it never names alternatives or states when to prefer crm_update_contact or crm_save_contacts. Usage is inferable rather than explicitly guided.

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