update_contact

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

With no annotations provided, the description carries full weight for behavioral disclosure. It explicitly explains the replacement semantics ('Each provided field WHOLLY REPLACES the stored value') and provides a concrete example, while also stating the required read-write scope. It is transparent about partial updates and clearing behavior, though it does not detail error cases or response format.

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 sentences with no wasted words, front-loading the primary purpose and then adding essential behavioral context. It is an ideal length for a mutation tool with this complexity.

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 tool's complexity (7 parameters, nested objects, arrays, no output schema, no annotations), the description covers the core behavioral context: partial update semantics, array clearing, scope requirement, and what fields remain untouched. It lacks explicit mention of error handling or return value, but these are not expected given the schema and overall tool set.

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 schema descriptions cover 100% of parameters, so the baseline is 3. The description adds a cross-cutting semantic note about field replacement, but this generalizes what is already stated in individual parameter descriptions. It does not introduce significant new meaning beyond 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 description clearly states the tool's function with a specific verb and resource: 'Update an existing contact.' This distinguishes it from sibling tools like create_contact, delete_contact, and get_contact, which have different purposes.

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 provides clear context for when to use the tool (updating an existing contact) and notes the required scope, implying it is not for creating or deleting contacts. However, it does not explicitly mention alternatives or exclusions, so it falls short of a perfect score.

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