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

The description adds useful behavior beyond the annotations: tags are merged rather than replaced, notes are appended, and events are emitted so automations can fire. This complements the idempotent and non-destructive hints, though it doesn't mention what happens to omitted fields on update.

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 tightly written sentences with zero filler. It front-loads the core upsert behavior and follows with key operational details.

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?

Given the rich schema, output schema, and annotations, the description covers the critical upsert semantics and side effects. It could be slightly more complete by stating whether omitted fields are preserved on update, but it is sufficient for correct invocation.

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 the baseline is 3. The description adds semantic value by identifying email as the upsert key and clarifying that tags merge and notes append, which goes beyond basic parameter documentation.

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 a specific verb and resource: create or update a CRM contact keyed by email. It captures the upsert behavior well, but it does not explicitly distinguish itself from the sibling update_contact or find_contact tools.

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 gives clear usage context by framing the tool as the way to "save a lead" and noting that email is the only required field. It does not explicitly say when to prefer update_contact or find_contact, but the primary use case is unambiguous.

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