Call statistics

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true. The description reinforces this with 'Read-only analytics, changes nothing and spends nothing,' adding that it is cost-free and idempotent, which is consistent and slightly extends the annotation info.

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: 3 sentences covering purpose, read-only nature, period and filtering, and alternative tool. No filler or redundant information. Every sentence is valuable and front-loaded.

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 read-only analytics tool with annotations providing safety guarantees, the description covers the main aspects: metrics, period, filtering, and alternatives. It lacks explicit mention of output format (no output schema), but given the simplicity and the presence of annotations, it is largely complete. Slight gap for output details.

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 has 100% description coverage for all 4 parameters. The description repeats the period format (dateFrom..dateTo YYYY-MM-DD) and itemIds behavior ('Without itemIds — across all of the user's listings'), which adds no new information beyond the schema. Baseline 3 is appropriate.

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 it returns aggregated CALL statistics for listings over a period, listing the metrics (total/new/answered/new answered) and breakdown by day. It distinguishes itself from the sibling tool 'items_post_item_stats_shallow' for views/contacts, making its purpose clear and unique.

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 provides explicit guidance on when to use this tool vs. alternatives: 'For views/contacts, use items_post_item_stats_shallow.' It also clarifies the behavior without itemIds (across all listings) and the period format, giving clear context for usage.

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