Contacts: Contact Filter

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

Annotations declare a non-read-only, open-world, non-idempotent profile, and the description corroborates this by disclosing the raw HTTP surface (POST endpoint) and the auth requirement (User API key or Agent bot API key via `api-access-token` header). The Persian/Farsi and Arabic-Indic digit passthrough note is genuinely useful behavioral context not derivable from annotations or schema.

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?

The definition is front-loaded with the purpose, then method, auth, and body fields in compact fashion. The closing digit-encoding sentence is somewhat tangential but short and adds distinct value; overall little waste.

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?

With no output schema, the description supplies the endpoint, HTTP method, auth scheme, body-field pointer, and the extra_body escape hatch, which is adequate context for calling this nested-payload filter. Sibling differentiation is the main gap, but the mechanics of invocation are well covered.

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 schema already fully documents page, payload, account_id, and extra_body. The description only restates that 'payload' is the body field and that extra_body carries unlisted keys, adding no syntax or format detail beyond the schema. 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 clear verb+resource: 'Filter contacts with custom filter options and pagination.' This distinguishes it from plain listing, and the 'custom filter options' phrasing signals the structured payload approach. However it never names the alternatives (gapify_list_contacts, gapify_search_contacts), so the agent must infer the boundary itself.

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 is only implied. The description mentions custom filter options and pagination but gives no explicit when-to-use or when-not-to-use versus siblings like search_contacts or list_contacts. Auth prerequisites and body-field naming are present, but routing guidance to alternatives is absent.

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