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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the agent knows this is a non-destructive mutation. The description adds important behavioral context by indicating that the reply must use the version last read, implying an optimistic-concurrency requirement, but it does not explain conflict behavior, notification effects, or idempotency semantics.

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 a single front-loaded sentence with no filler. It states the action and the key version condition without unnecessary repetition.

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 non-destructive mutation tool with four required, undocumented parameters and no output schema, the description is too thin. It omits idempotencyKey semantics, body constraints, caseId sourcing, and expected conflict handling, leaving the agent with gaps it cannot resolve from the schema alone.

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 0%, so the description must carry parameter meaning. It clarifies expectedVersion as 'the version you last read,' which is valuable, but it says nothing about the required idempotencyKey, the caseId pattern/source, or the body length limits and purpose.

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 uses a specific verb ('Reply') and resource ('support requests'), making clear it adds a message to an existing case rather than reading, listing, filing, or marking one. It is readily distinguishable from the sibling support-case tools such as get_support_case, list_support_cases, and mark_support_case_read.

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?

Usage is implied by the action itself: this is the tool for replying to an existing support case. The phrase 'using the version you last read' hints at a prerequisite prior read, but the description does not explicitly state when to use this versus alternatives or what to do if no last-read version exists.

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