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

With no annotations, the description bears full responsibility for disclosing behavior. It states 'value discarded', which suggests the value is not retained, but it does not clarify which value is discarded, what output is returned, or whether any side effects occur. The other parameters' discard behavior is only implied in schema descriptions, not the tool description.

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 extremely short, but brevity is not conciseness here—it omits essential information about which parameter to use and what the tool returns. It does not front-load the most critical fact (how to pass the sort code) and feels under-specified rather than clean.

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?

Given nine optional parameters, no output schema, and no annotations, the description is far too thin. It says nothing about return values, error behavior, or how the 'shape' check is applied to the inputs. An agent cannot correctly invoke this tool based on the provided description and 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?

Even though schema description coverage is 100%, the tool's description does not link any parameter to the sort code shape check. The schema defines ref, url, city, etc., but none is identified as the sort code value, so the description adds no semantic value to the parameters and leaves the agent unable to construct a valid call.

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 identifies a specific validation target ('UK sort code 6-digit shape') and distinguishes it from sibling shape checkers like domain-shape or jira-key-shape. However, it fails to tie this purpose to any of the nine declared parameters, so an agent cannot tell which input carries the sort code, making the stated purpose hard to apply.

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?

No guidance is given on when to use this tool versus alternative shape validators or how to prepare input. The description does not mention any scenarios, prerequisites, or exclusions, leaving the agent to guess when this check is appropriate.

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