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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered without the description's help. The description adds the identifier-source hint but does not explain what 'Replace' destroys (e.g., whether the prior text is fully overwritten) or that reruns are safe via the idempotencyKey parameter.

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?

A single short sentence that front-loads the operation and tucks the identifier source into a parenthetical. No filler or redundancy.

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 three-parameter mutation with no output schema, the description covers the core operation and the prerequisite, and annotations carry the safety profile. It is nonetheless thin on the semantics of replacement and on the optional idempotencyKey's retry behavior, which an agent must infer from the schema.

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%, so the baseline is 3, but the description adds real value by telling the agent where welcomeId comes from (list_welcome_messages) — notably the schema's own welcomeId description is garbled ('Delete and enrollExisting'). The message parameter's meaning is already clear from 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 ('Replace the text of a welcome message'), which cleanly separates it from create_welcome_message and delete_welcome_message. It also names the sibling that supplies the required identifier, though it does not explicitly contrast its purpose with those siblings.

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 parenthetical '(welcomeId from list_welcome_messages)' implies a prerequisite workflow, which is useful. However, there is no explicit when-to-use guidance, no mention of when an edit is preferable to deleting and recreating, and no exclusions.

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