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

Annotations already declare read-only, non-destructive, open-world behavior, so the bar is lower, and the description still adds meaningful traits: no image output, a 'short' output length, and the privacy guarantee that 'the answers are not stored.' It omits the non-idempotency nuance (identical input may yield a different portrait), which is the one behavioral trait left unstated.

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 short, front-loaded sentences with the core capability first, then constraints, then the privacy note. The opening clause 'an imagined partner, in words' partially echoes the title, which is the only mild redundancy.

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?

An output schema exists, so return values need no explanation, and the description covers modality, output length, input source, and data handling for a one-parameter tool. Only the variability of repeated calls and the exact shape of the generated portrait are left implicit.

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?

With a single parameter at 100% schema description coverage, the schema already explains that 'answers' is free text describing what the person values, with not-stored and not-a-photo caveats. The description's 'from answers you give' adds only marginal framing beyond that, so the 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?

The description names a concrete verb and output: it 'writes a short portrait' of 'an imagined partner' from supplied answers, which is more than a restatement of the title. It does not reference the sibling tools, but those (get_feedback_reply, index_tools, submit_feedback) are unrelated domains, so the absence of routing language costs little.

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?

It gives clear scope boundaries — 'No photos, no faces, no matching with real people' — which steers an agent away from mistaking this for an image generator or a real-person dating tool, and 'from answers you give' signals the required input. It stops short of naming alternative tools or stating when this should be preferred over other generation tools.

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