Contact Update

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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the agent knows this is a non-destructive mutation that is not idempotent. The description reinforces the merge semantics with "only provide fields to change", but adds nothing about permissions, error behaviour, or side effects on unmentioned fields (the schema covers the latter).

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 imperative sentences, with the core action front-loaded and the usage caveat second. Nothing is wasted, though the description is on the thin side for a nine-parameter mutation tool.

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 mutation tool with no output schema, the definition leans entirely on annotations plus a 100%-documented schema. That combination is just enough to call it correctly, but the description itself contributes almost no behavioural or return-value context.

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%, including helpful cross-references such as contact_field_list and organization_list, so the schema carries the parameter burden. The description's only addition is the partial-update instruction, which is already echoed by the `fields` description ("Fields not listed keep their value"), so baseline 3 is right.

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 (update) and resource (contact), so the agent knows exactly what the tool does. It does not distinguish itself from neighbours like member_update or organization_update, but the contact-scoped name makes the target 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?

"Only provide fields to change" gives the partial-update contract, which is genuine usage guidance for a PATCH-style call. However, it never says when to prefer this over contact_create or contact_delete, nor what happens if a contact id is invalid, so usage is merely implied.

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