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

The annotations already cover safety (readOnly, idempotent, non-destructive), yet the description adds non-obvious operational details: every started minute of the session costs credits, and the session ends on close or 3 minutes after the last call. It also discloses the return shape (JPEG plus URL and title), which the annotations do not touch. This is context an agent could not derive from structured fields.

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?

Two sentences, each earning its place: the first front-loads what is returned and why it matters visually, the second carries the cost and lifetime constraints. No restatement of the name or title.

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 parameters and no output schema, the description carries the full burden and meets it: it explains the return value (image, URL, title), the visual-content motivation, and the session cost/lifetime. Nothing an agent needs to decide whether and when to call is missing.

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?

The tool takes no parameters and the schema has additionalProperties false, so there is nothing to mis-specify; the description correctly implies the call acts on the current browser page state rather than on caller-supplied input. Baseline 4 applies for a zero-parameter tool.

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 definition states a concrete verb and resource: it returns a JPEG image of the visible portion of the current page, plus that page's URL and title. It also scopes the value proposition ('boards, canvases and layouts that the page text does not show'), which distinguishes it from the text-reading sibling without needing to open a schema.

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?

The clause 'that the page text does not show' signals the condition that makes a screenshot the right call over textual reading, giving clear usage context. It stops short of explicitly naming cotlet_browser_read as the alternative, so the routing is inferred rather than stated.

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