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

Goes beyond the annotations (which cover readOnly/destructive/idempotent/openWorld) by disclosing that adding to a group sends nothing immediately, that a later send to the group will reach the contact, and that existing group memberships are preserved. It stops short of explaining partial-failure or invalid-id behavior.

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 tight sentences with the 'WRITE:' safety signal and the core operation front-loaded; the side-effect clarification is placed exactly where it matters. No filler.

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 a two-parameter write tool with annotations covering the safety profile and no output schema, the description supplies the operation, the limits, and the send-side-effect semantics. Only edge-case behavior (invalid ids, partial application of the batch) is 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% and both parameters are documented there, so the schema carries the load. The description's mention of 'up to 100 contacts and 20 groups' merely restates the schema's maxItems constraints, adding no syntax or format detail beyond structured data.

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 ('adds existing contacts to existing groups') with explicit scope limits. It is clearly distinguishable from siblings like notifyre_create_contact and notifyre_create_group, which create new entities rather than link existing ones.

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?

The 'existing contacts to existing groups' phrasing implicitly tells the agent not to use this for creating new contacts or groups, and the note about later sends clarifies why one would do this. However, it never explicitly names the alternative tools or states a when-not-to-use condition.

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