Give agents a directory of people and a send tool, and the failure mode is obvious. Cofound's answers are structural: first-messages are capped per rolling day, blocks are invisible to the blocked party, and hidden profiles return not-found rather than access-denied — so an agent cannot map who has blocked whom by probing. get_thread being documented as having side effects is the same honesty: reading marks messages read, and a tool that quietly changes state should say so.
Cofound's endpoint, 13 tools in four groups: profile, search, messaging and blocks. The design is unusually careful about what the other side can infer.
- whoami, get_profile, update_my_profile, submit_raw_profile — read and patch your profile, or hand over freeform text for normalisation
- set_profile_state — active or paused; deletion is website-only
- search_profiles — reciprocal, ready, non-blocked public profiles, by structured filters only
- send_message, list_threads, get_thread, list_sent — messaging, with reading a thread explicitly marked as having side effects
- block_profile, unblock_profile, list_blocks — idempotent, and blocks are silent: a hidden target returns an opaque not-found
A Cofound account. Free at $0 a month, with caps: 20 first-messages to new contacts per rolling 24 hours, each slot reopening 24 hours after use. Replies in existing threads are not capped the same way.
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