Create or update contact

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

Annotations declare destructiveHint=true but say nothing about the mechanism; the description supplies exactly the missing context: the first call writes nothing and returns a preview plus confirm_token, and nothing is persisted until the token is replayed with identical arguments. That is disclosure well beyond the annotation layer.

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?

Three compact sentences, front-loaded with purpose followed by the two-step constraint. No filler, and the highest-risk information (nothing is written on the first call) is stated plainly rather than buried.

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?

With no output schema, the description compensates by describing what the first call returns (a preview and a confirm_token). Together with the partial-update semantics and the confirmation gate, an agent has everything needed to call this mutation tool correctly.

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 only 13%, so the description must carry the load. It does add key semantics for contact_id (selects update mode) and confirm_token (two-step gating) plus the important partial-update rule that 'only provided fields change', but the six field parameters (name, email, tags, notes, phone, company) remain undocumented.

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 states the specific verb and resource (create/update a contact) and, critically, the rule that selects the mode: update happens 'when contact_id is given'. An agent can distinguish this from delete_contact, get_contact, and upsert_deal without opening any 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?

It gives an explicit operational condition (contact_id present → update; absent → create) and a mandatory workflow (preview first, apply only after user approval). It does not name sibling alternatives or exclusions, so it falls short of a full when/when-not/alternative statement.

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