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

Goes well beyond the annotations (which only flag destructive/idempotent/openWorld) by disclosing that only the default language is written, that other languages route through configure_survey_language, that the text may be saved-but-not-displayed, that willDisplay reports which case applies, and that the write is verified by re-reading. This is unusually rich behavioral context.

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?

Front-loads the core action before the caveats and alternatives. Dense but every clause carries information; slightly long, though nothing is truly redundant.

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 a mutation tool with an output schema present, the description covers the display conditions, language scoping, permission requirement, alternative tools, and the willDisplay reply field. Nothing an agent needs to call it correctly 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?

Schema coverage is already 100%, so the baseline is 3, but the description adds genuine meaning: it clarifies that `title` renders above the message and that `message` accepts HTML. Minor added value over 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 and resource ('Sets the survey's GLOBAL end-screen message') and immediately distinguishes it from the standard thank-you text and from siblings. The contrast with add_end_page and configure_survey_language makes the scope unambiguous.

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?

Explicitly states when the message appears (standard end screen only) and when it does not (redirect/restart end behavior saves but does not display), plus the routing rule for branch-specific text via add_end_page. It also states the required permission.

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