update_kpi

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

Discloses key behavioral traits: the merge semantics ('Any omitted property is left unchanged') and the create-if-none fallback. Since no annotations are provided, the description carries the full burden, and it does so adequately, though it does not mention permissions or failure modes for missing measures.

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 with a clear verb-first structure. Every word adds value, and the description is front-loaded with the primary action and distinctive properties.

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?

Covers purpose, usage context, and critical behaviors (create-if-none, merge semantics) in a compact format. For a tool with 8 parameters and no output schema, it is fairly complete, though a brief note on return values or error conditions would make it more comprehensive.

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 descriptions cover 5 of 8 parameters; the description adds semantic grouping by naming the categories (trend expression, target format string, descriptions). Required parameters (table, measure, sessionId) lack descriptions but are self-explanatory. The description compensates reasonably for the 63% schema coverage.

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 explicitly states the action ('Extend a measure's KPI') and lists specific properties (trend expression, target format string, descriptions), clearly distinguishing it from the sibling set_kpi tool. The mention of 'beyond set_kpi' reinforces the specific purpose.

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?

Names set_kpi as the base tool and explains that this extends beyond it, providing clear context for when to use it. Also notes that it creates the KPI if none exists, which helps determine applicability. Lacks explicit exclusions or alternative comparisons beyond set_kpi.

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