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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the write/non-destructive profile is covered. The description adds nothing beyond that — no statement about duplicate detection or merging, which account receives the contact, or what identifier is returned for later contacts_update/contacts_get calls.

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 zero filler. It is efficient but arguably under-written for a mutation tool with seven parameters.

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 simple create operation with full schema coverage and annotations, the essentials are present. However, with no output schema, the description should say what comes back (a contact resource/ID) and whether duplicates are created, which an agent needs before follow-up calls.

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 all seven fields including the optional account selector are already documented in the schema. The description supplies no additional semantics (e.g., whether phone is free-form, whether notes accepts multiline), so 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?

The description gives a specific verb and resource ('Create a new contact in Google Contacts'), which cleanly separates it from contacts_update, contacts_get, contacts_search, and contacts_list. It stops short of noting anything distinctive such as duplicate handling or the account scoping that the schema exposes.

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?

There is no explicit when-to-use guidance: nothing says to search for an existing contact first, nothing distinguishes creating from updating via contacts_update, and no prerequisites are mentioned. Usage is only implied by the verb 'Create'.

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