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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral facts: unsubscribed contacts are omitted unless include_unsubscribed is true, and the unsubscribe key is never returned, which tells the agent what it will and won't see in results.

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?

Compact, front-loaded sentences that each carry a distinct fact (filters, pagination base, exclusion defaults, hidden field, endpoint). The trailing endpoint note is mildly redundant with the title but confirms the read semantics of the POST.

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 8-parameter read tool with no output schema, the description covers filtering, pagination origin, and result-content caveats well enough to call it correctly. It stops short of describing the response envelope or pagination metadata, which the absent output schema leaves undocumented.

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%, so the baseline is 3. The description largely restates schema text (page starts at 0, search_query matches name, type keeps contacts with that number) and says nothing about sort_by, sort_dir, or limit, adding no syntax or format detail beyond the schema.

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?

Starts with a precise verb+resource ('Search the address book') and names the exact endpoint (POST /addressbook/contacts/search), making it instantly distinguishable from the singular notifyre_get_contact and from the unrelated list_* tools.

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?

Explains when each filter applies (search_query matches name, type keeps contacts with that number, group_ids limits by group) and states the default exclusion of unsubscribed contacts, giving clear context for how to narrow results. It never routes the agent away from alternatives (e.g. get_contact for a single contact), so it stops short of a 5.

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