update_contact

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose the key behavior that unspecified fields remain unchanged (partial update). It does not mention side effects, validation rules, or whether null values clear fields, but the core mutation behavior is clear from '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?

A single, front-loaded sentence with every word contributing meaning. It communicates the operation, the target resource, and the partial-update rule with no redundancy.

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 low-complexity tool with three parameters and no output schema, the description is nearly sufficient. Combined with the schema's id description ('from list_contacts'), the agent has what it needs to call correctly. It stops short of describing error cases or null semantics, so it is not fully 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 coverage is only 33%, but the description adds important meaning to the optional name and email parameters: send only those you want to change. This tells the agent that omitting a parameter preserves its current value, which is not evident from the schema alone.

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 ('update') and resource ('a contact'), plus a qualifier ('Partially') that distinguishes it from full-replace operations. The sibling context (create_contact, delete_contact, list_contacts) reinforces that this is the targeted modification tool.

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 phrase 'only send the fields you want to change' implies this is for modifying existing contacts and not for creation or deletion. However, it does not explicitly state when to use it over alternatives or when not to use it, so usage guidance is implied rather than fully specified.

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