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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuine behavioral context beyond that: the tool works in both directions, and supplying a status byte triggers per-bit explanation of the 8 DTC status bits.

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?

Two dense sentences that front-load the primary transformation and then add the optional status-bit behavior. No filler, no repetition of the tool name.

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?

With no output schema, the description carries the return-value burden and largely does so, naming the SAE J2012 code plus failure type byte and the status-bit breakdown. Exact output formatting (field names, layout) is still left implicit, which is the only gap.

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 100%, so the baseline is 3. The description goes beyond the schema by clarifying the accepted input forms for dtc and by explaining what the optional status byte actually produces (per-bit decoding), which the schema only labels as 'Optional status byte'.

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 precise verb (Convert) plus resource (3-byte UDS DTC) and both directions of the transformation, with concrete examples of each format. An agent can distinguish this DTC-specific tool from generic siblings like decode_uds without opening any schema.

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 input forms described ('01 23 45' or 'P0123-45'), but there is no explicit statement of when to reach for this versus decode_uds, decode_isotp, or uds_reference. The bidirectional nature is clear; the routing context is not.

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