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

Annotations only declare readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false. The description goes well beyond that by disclosing the real side effects (owner notification, email delivery) and dual rate limits (per business and directory-wide), which are exactly the traits an agent needs before calling a mutating tool.

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 sentences, no filler, and the side-effect warning is front-loaded right after the purpose. The second sentence is dense with two distinct ideas (side effects and rate limits), which slightly blurs the structure.

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?

An output schema exists, so return values need not be explained, and the annotations plus description together cover mutation, openness, non-idempotency and rate limits. Minor gaps remain around authentication/identity expectations and confirmation behavior, but the core calling context is present.

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 33%: message and business are documented, but subject, sender_name, sender_email and sender_phone carry no schema descriptions. The description adds nothing about any parameter, so it fails to compensate for the coverage gap on a 6-parameter tool.

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 ('Send a message to one business') and the scoping word 'one' immediately distinguishes it from directory-level or broadcast siblings like search_businesses. An agent can route to it without opening the 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 a clear usage condition — send one considered inquiry rather than a broadcast — plus the rate-limit constraint that shapes appropriate use. It stops short of naming an alternative tool or spelling out when-not to use it, so it is strong context rather than full routing guidance.

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