compare_runs

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

With no annotations available, the description carries the full burden. It discloses the data source ('stored metrics'), the cardinality ('two or more runs'), and a key non-behavior ('never looks up the latest HTML report'). It does not discuss output format or error cases, but the read-only diff behavior is reasonably transparent.

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 short sentences, front-loaded with the core function, followed by a meaningful caveat. There is no redundant fluff or repetition of schema information.

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 simple single-parameter tool, the description covers the core intent, the required input semantics, and a key behavioral boundary. The only notable gap is that it does not describe what the diff output looks like, but the absence of an output schema and the tool's low complexity make this acceptable.

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?

The schema provides no property descriptions (0% coverage), so the description must compensate. 'Two or more runs' adds meaningful semantics: the run_ids parameter should contain at least two run identifiers, which is not otherwise stated. It doesn't specify ID format, but the parameter name makes that reasonably clear.

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 clearly states a specific operation ('diff'), a specific resource ('stored metrics'), and scope ('two or more runs'). It also explicitly distinguishes itself from HTML-report lookup, which helps an agent differentiate it from report-oriented tools.

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 description clearly implies when to use it: when comparing stored metrics across multiple runs. The caveat that it never looks up the latest HTML report provides an exclusion, but it does not name an alternative tool or describe specific competing workflows.

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