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

Annotations already declare destructiveHint=true and idempotentHint=true, so the description doesn't need to repeat those. It adds the key behavioral trait that other screens remain untouched and explains the concurrency safety advantage. It does not contradict annotations and provides useful context beyond them.

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?

The description is two sentences, front-loaded with the primary action and scope, then a targeted comparison to the alternative. Every sentence earns its place with no fluff.

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?

The description covers what the tool does, when to use it, and a key concurrency benefit. The output schema handles return details, and the input schema thoroughly documents block types and fields. No essential information is missing for correct invocation.

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%, with each parameter (courseId, screenId, title, blocks) already documented in the input schema. The description does not add new parameter-level meaning beyond the schema, so it meets the baseline for covered schemas without adding extra value.

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 clearly states the action: 'Replaces one screen's title and/or blocks, leaving every other screen untouched.' This is a specific verb (replaces) and resource (screen) with an explicit scope (single screen). It also differentiates from the sibling update_course by noting it's for editing content and reads/writes a single screen.

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 description explicitly directs when to use this tool: 'Prefer this over update_course for editing content' and explains the reason (avoids overwriting concurrent edits elsewhere in the course). This is a clear when-to-use with an alternative named and rationale given.

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