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

Annotations already establish this as a read-only, idempotent, non-destructive, closed-world read. The description adds the useful caveat that 'Tone is not scored' and sketches the response shape (head-to-head counts per engine, quoted snippets with receipt ids), which goes a bit beyond annotations. It says nothing about cost, rate limits, or failure behavior when a competitor name does not match.

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?

Front-loaded with the purpose ('Use this to see...') followed by the output summary and one usage rule, with no filler. The first sentence is dense but each clause carries distinct information, so nothing is wasted even if it reads as a long single sentence.

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 enumerated, yet the description still previews the payload (counts, snippets, receipt ids) plus the 'tone not scored' limitation. Combined with the omit-competitor behavior, an agent has what it needs to call the tool correctly; only cross-tool routing guidance is absent.

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 and the schema already documents both parameters. The description adds meaning the schema lacks: omitting competitor changes the call into an enumeration of available competitors, which is genuine optionality semantics not present in the schema text.

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+resource ('see what each engine said about the client against one competitor in one run') and scopes it to a single run and single competitor, which separates it from the run-comparison sibling. It does not name or contrast any sibling tool explicitly, so an agent must infer which of the 15 siblings to use for related questions.

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?

Gives one concrete usage rule ('Omit competitor to list the competitors available'), which is real routing guidance for the optional parameter. It offers no when-not/exclusion guidance and does not point to alternatives such as get_displacement or compare_runs for adjacent questions.

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