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

Annotations already declare idempotentHint=true and destructiveHint=true, so the description sensibly adds context the annotations cannot: sends are 'subject to consent policy' and 'first sends may require human approval.' That consent/approval detail is meaningful behavioral disclosure, though it doesn't explain why the operation is flagged destructive.

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 tightly written sentences, with the routing trigger front-loaded and the consent/approval caveat following. No filler and nothing redundant with the schema.

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 annotations cover the safety profile. The description adds the consent and approval prerequisites an agent needs, leaving only minor gaps (e.g. what consent-policy rejection looks like) unaddressed.

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%: recipient already documents how to resolve local names (find_connections or list_circles) and idempotency_key documents retry safety. The description adds no parameter-level meaning beyond the schema, so the 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?

States a concrete verb+resource ('Sends text') and the target type ('someone or a circle'), making the core action obvious. It does not explicitly distinguish itself from the close sibling messages.reply, but the trigger framing ('when the human asks you to message someone') implies a new outbound message rather than a threaded reply.

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?

Provides an explicit when-to-use trigger plus a concrete example ('asking the family circle which weekend works'). It stops short of naming alternatives such as messages.reply or federation.messages.draft, so an agent must infer the boundary, but the usage context is clear.

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