render

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

With no annotations, the description carries the full burden and does so well: it declares 'Read-only: the board, the file and the undo history are untouched', states defaults (max_px 1400, padding 24), the hard limits (16–3000 px, 4x max enlargement), and the automatic downscaling above 4 MiB surfaced via `note`. The only gap is that it never explicitly says what the returned payload looks like (image content vs. URI), which matters for a no-output-schema tool.

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 safety, then framing modes, then decoration, then sizing. Every sentence carries distinct operational information—defaults, caps, or edge cases—with no redundant restatement of the name.

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 tool with a nested `region` object and no output schema, the description covers framing modes, sizing limits, file output, and read-only safety. The main missing piece is the shape of the response (how the image is returned, what `note` contains in the normal case), which matters given there is no output schema to fall back on.

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 coverage is 100%, so the baseline is 3, but the description adds genuine meaning beyond the schema: `show_ids` badge placement (top-left corner, middle of arrows), that pen strokes get no id, that `region` adds no padding, and the ids-vs-region exclusivity. It stops short of explaining `page` or `path` semantics beyond what the schema already says, keeping it at a 4 rather than 5.

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?

Opens with a specific verb and resource ('Returns a PNG picture of the board') plus scope options (whole page, region, ids). It distinguishes itself from siblings by naming what it is for ('to check your work visually') and referencing `export`, `update_object`, and `add_connector` as related tools, so an agent can separate it from export/describe_board without opening schemas.

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?

Gives explicit when-to-use ('to check your work visually'), mutually exclusive alternatives for framing ('give either, not both' for region vs ids), and a condition for the `output` parameter ('for clients that do not display images'). The routing logic between the two framing modes is fully spelled out rather than implied.

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