count

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, which cover the safety and idempotency profile. The description adds no extra behavioral context (e.g., return value or side effects), but does not contradict annotations.

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 concise at two words, which is efficient for a simple tool. However, it could include a bit more detail (e.g., 'Count the number of elements in the input array') without losing conciseness.

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?

The tool is simple, but the description lacks mention of the return value (the count). Given there is no output schema, the description should specify that the tool returns the count of elements. Otherwise, it adequately covers the input.

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?

With 0% schema description coverage, the description should compensate by explaining the 'numbers' parameter. The description only says 'Count elements,' which implies the parameter is the elements to count, but it does not explicitly clarify its meaning or format beyond 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?

The description 'Count elements' clearly indicates the verb (count) and resource (elements), and it distinguishes the tool from siblings like sum or avg which compute different aggregates. However, it could be slightly more explicit by stating 'Count the number of elements in the array.'

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 provided on when to use this tool versus alternative sibling tools (e.g., sum, avg). The description does not specify context or exclusions, leaving the agent without direction for tool selection.

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