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

Annotations already flag destructiveHint=true and idempotentHint=false, but the description adds real behavioral context beyond them: the effect is a persistent, global suppression ('from then on') that every outbound path honors. It stops short of saying what happens on duplicate input or what permissions are needed, so it is additive but not complete.

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 sentences, effect front-loaded, zero filler. Every clause carries information an agent needs.

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?

There is no output schema, so the description should ideally state what a successful call returns (e.g., count added, duplicates skipped), and the reason parameter is undocumented in both schema and description. The core effect is communicated well, but the picture is incomplete for a destructive, non-idempotent mutation.

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?

With only 33% schema coverage, one of three parameters has a schema description (organization_id). The description only weakly maps to phone_numbers ('Add numbers') and gives no meaning for the reason parameter, whose 160-char constraint appears nowhere. Partial compensation only.

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: 'Add numbers to the workspace do-not-call register.' The resource is unambiguous and distinct from sibling tools like update_number_rules or authorize_outbound. It does not, however, explicitly contrast itself with any sibling, which is what a 5 would require.

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?

Usage context is implied by the register's purpose (suppressing outbound contact) but the description never says when to reach for this tool versus update_number_rules, evaluate_outbound_policy, or check_number_requirements, and gives no exclusions or prerequisites. Adequate but with a clear routing gap.

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