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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds useful context: it reads live session state (not persisted design data) and requires a private, expiring sessionToken, implying an auth-like capability requirement.

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?

Three compact sentences, no waste: what it reads, what it's for, and what it needs. Purpose and scope are front-loaded before the prerequisite.

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, so the description carries the burden of describing returns; enumerating designs, elements, print areas, previews and the last changed object covers the content an agent needs. It stops short of describing the shape/nesting of those objects, but that is minor for a simple read.

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% and both parameters are documented in-schema as coming from start_design_session. The description only echoes that they are required, adding no format, expiry, or validation detail beyond the schema.

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 ('Read') and enumerates the resource scope precisely: this session's designs, elements, print areas, previews and last changed object. An agent can tell it's the session-read tool, though it never explicitly contrasts with the nearby get_design_request sibling.

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?

'Use it to resolve an edit's target' gives a concrete triggering scenario, and the second sentence states the prerequisite inputs (subject, sessionToken). No when-not guidance or named alternatives, so it stops short of a 5.

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