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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is covered. The description usefully adds output shape ('hex with an annotated breakdown') and the input convention that numeric strings are hex, both of which go beyond the structured fields.

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 sentences, purpose front-loaded, no filler. The 16-service enumeration duplicates the schema enum and occupies most of the text, a minor redundancy in an otherwise tight definition.

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 23-parameter tool without an output schema, the description compensates by stating the output format and the hex-string input convention. It lacks per-service guidance on which parameters combine, though the schema descriptions cover most of that ground.

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 87%, so per-parameter meaning is largely documented in the schema. The description adds one genuinely valuable cross-cutting convention ('Numeric strings are hex') that applies to many string parameters and is not itself in 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 ('Build a UDS request as hex with an annotated breakdown'), plus the full set of supported services. The builder framing distinguishes it from the decode_* siblings, though it never names them explicitly.

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 enumerated service list implies when the tool is applicable, but there is no explicit when-to-use, when-not, or routing to alternatives such as decode_uds or uds_reference. Usage is inferable rather than stated.

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