update_contact

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

With no annotations, the description carries the full behavioral burden and discloses very little: it does not say which fields are mutable, what happens if the name matches multiple contacts, whether macOS will prompt for Contacts access, or what is returned on success/failure. 'Updates' signals a mutation but gives no sense of scope or side effects.

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 no filler; the parenthetical 'Contacts.app' is mildly redundant next to 'Mac's Contacts app' but aids disambiguation. Nothing needs to be cut.

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?

A tool described as updating a contact but exposing no parameters leaves an agent unable to determine how to identify the contact or specify changes; the description does not resolve that gap. With no annotations and no output schema, more disclosure about behavior and inputs was required.

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 declares zero properties, so by the baseline rule this would be a 4, but the description references 'contact_id' and 'name' as lookup keys that do not appear in the schema at all. That mismatch is actively misleading rather than helpful, pulling the score down from the zero-param baseline.

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?

States a specific verb (updates) and resource (a contact) and pins down the target system as the Mac's Contacts.app, which distinguishes it from the M365/Outlook contact siblings. It also names the lookup mechanism (contact_id or by name), though that detail is undercut by the empty schema.

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 never says when to reach for this tool versus m365_update_contact, create_contact, or the other contact siblings, nor does it state prerequisites such as an existing contact or macOS automation permission. Only implied usage ('if you want to modify a Mac contact') is available.

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