cost_summary

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

No annotations are provided, yet the description carries the full behavioral burden: it declares read-only status, clarifies the pricing basis (list price, not discount), and explains the completeness caveat (usd_complete=false with unpriced_skus). That is exactly the context an agent needs to interpret partial results.

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, then pricing caveats, then the usage routing — three sentences plus a directive, none of which are filler. Every clause adds decision-relevant 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?

With no output schema and no annotations, the description compensates fully by naming the returned fields (per-product, per-day, usd_complete, unpriced_skus) and the read-only/list-price semantics. An agent can interpret results without opening anything else.

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 description coverage is 0% and the sole `days` param has no schema description, but the description supplies its semantic range (integer 1..365) and ties it to the reporting window. It doesn't note the 30-day default, keeping it just under a 5.

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 ('Orient on spend') plus the exact resource dimensions returned: total list-price cost, cost per product, and per day. The closing clause ('overall bill shape') distinguishes it from the analytic siblings like find_waste and explain_cost_spike.

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?

Explicitly says 'Use before find_waste when you need the overall bill shape', giving a concrete placement in the workflow and an alternative it precedes. It doesn't exclude scenarios for the other four siblings (top_cost_drivers, cost_review_report), so it falls short of a full when/when-not map.

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