write_data_by_identifier

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

With no annotations, the description carries the burden well: it discloses that this is a mutating write, typically requires extended session and security access, and should be user-confirmed before execution. It omits error/reversibility behavior, but the safety-relevant traits are covered.

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 short sentences, front-loaded with the service identity, followed by input format, prerequisites, and the confirmation warning. No wasted text.

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?

An output schema exists, so return values need not be described. However, for a security-sensitive write with an undocumented required 'did' parameter, the description should say more about what the identifier is and failure behavior to be fully complete.

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 0%, so the description must compensate. It explains the two value input formats with examples ('00 64' or text), which is useful, but it leaves the required 'did' parameter entirely unexplained.

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 names the UDS service (0x2E WriteDataByIdentifier), a specific write operation on a data identifier, which is distinguishable from the read_data_by_identifier sibling. It is clear but does not explicitly contrast itself with 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?

It gives practical prerequisites: 'Usually needs the extended session and security access' and 'Confirm with the user before writing.' That is clear usage context, but it never names alternatives or conditions for when not to use it.

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