contacts_add

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

With no annotations, the description carries the full behavioral burden and delivers almost nothing: it does not mention duplicate handling, what happens on partial failure, auth/permission needs, or how the dry_run/confirm semantics in the schema apply to a create. Saying only that it returns the new contact id leaves the mutation profile undisclosed.

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?

Two short sentences, operation front-loaded before the return value, with zero filler. Nothing in the text is redundant with itself.

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 10-parameter mutation tool with no annotations and no output schema needs more than a single-line statement. Nothing explains that zero parameters are required or what minimum identity (name/email/phone) makes a useful contact, and the write semantics are left entirely to the schema.

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 100%, so every parameter is documented in the schema itself (including the max-10 email/phone limits and the confirm/dry_run behavior). The description adds no parameter meaning beyond that, so the baseline 3 applies.

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 and resource ('Create a contact in Contacts.app'), which cleanly separates it from the sibling contacts_edit and contacts_remove. It does not explicitly name those alternatives, so it falls short of a 5, but the operation is unambiguous.

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?

No when-to-use guidance, no prerequisites, and no pointer to alternatives such as contacts_edit for updating an existing contact. The agent must infer that this is the creation path from the verb alone.

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