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

Annotations only supply destructiveHint=false, so the description carries real weight here: it declares this is a write, states the endpoint (POST /contacts), and explicitly warns 'Not idempotent: calling twice creates two contacts' — a behavioral trait no annotation exposes. It stops short of permissions/auth requirements or what the response returns.

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?

Four short clauses, front-loaded with the write marker and cardinality, then requirements, then the idempotency warning. No filler — every phrase adds information an agent needs before calling.

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 an 18-parameter creation tool with no output schema and near-zero schema descriptions, the definition covers only its three required fields. An agent has no guidance on how to populate name vs firstName/lastName/companyName, when to use doctorType versus type, or limits like maxItems=5 on phoneNumbers, leaving most of the call surface unexplained.

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 11% across 18 parameters, so the description must compensate — and it barely does. It adds meaning only for `type` (Splose contact type, copy from existing) and restates that name/email are required; the 15 other properties (phoneNumbers array, doctorType enum, address fields, firstName/lastName split) get no explanation beyond their names.

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?

Opens with an explicit verb/resource pair ('WRITE: adds ONE contact') and enumerates the concrete roles it covers (GP, plan manager, referrer, payer), which sharply separates it from generic record-creation tools. 'ONE' also signals cardinality unambiguously.

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?

Names the required fields and routes the agent to splose_list_contacts to discover valid `type` values, which is genuinely useful. However, it never addresses the obvious sibling confusion — when to create a contact versus splose_create_patient — and gives no preconditions or dedupe-first guidance despite admitting duplicates are possible.

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