Save something she learned about this person

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

With no annotations, the description carries the full burden and does disclose meaningful behavior: the fact persists across sessions and surfaces on any body, it is visible on 37soul.com where the person can pin, edit, delete and export it, and content is constrained to one short item. It does not address idempotency/dedup, error behavior, or what is returned after saving, so it stops short of a 5 for a write tool with no annotation coverage.

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?

Purpose is front-loaded in the first clause, followed by examples and then the exclusion rule. The examples earn their place by disambiguating person-facts from task-facts, though the list is slightly repetitive and the closing 37soul.com sentence is more discovery than guidance.

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 or annotation set, so the description must stand alone, and it covers persistence, cross-body visibility, user editability and the single-fact constraint. It omits return shape and failure modes, but for a simple single-content write tool this is close to sufficient.

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 kind (with its enum), content (min/max length) and host_id are already fully documented in the schema. The description reinforces the content semantics via examples and the "ONE short" constraint but adds no syntax or format detail beyond the schema, so the baseline of 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 specific verb ("Save") and resource ("ONE short fact about the PERSON") and clarifies the scope: persistent across every future session and across bodies. It also distinguishes itself from task/project memory, so an agent can separate it from "your own memory" and from write-oriented siblings like update_host or instruct_post.

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?

Explicit when-to-use with concrete examples ("Has a dog named Mochi", "Prefers being teased over being praised") and an explicit when-not with examples ("build commands, code style, tooling preferences, repo conventions"), plus where those belong. This is about as clear a routing rule as a description can give.

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