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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds value by disclosing that output includes 'blocked collections' and 'known gaps' — behavioral substance an agent would not otherwise know. Return shape is covered by the output schema, so no penalty there.

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, front-loaded with the core purpose, and the action directive is placed at the end where it is easily found. The enumerated list is dense but each item carries distinct meaning, so nothing is gratuitous.

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 strong annotations, an output schema, and zero required parameters, the description covers enough for correct invocation. The only gap is clarifying how the four optional filters scope the report, which the schema only partly addresses.

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 50%, and the description implies filtering dimensions via 'per-source counts' and 'numeric restaurant-price coverage' (mapping loosely to source/category). However, the countries parameter and the relationship between the city/source/category filters and the report are not clarified 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 uses a specific verb ("Report what BudgetAtlas actually holds") and enumerates exactly what resource is covered: cities, per-source counts, lodging date/occupancy cohorts, restaurant-price coverage, blocked collections, gaps. This clearly marks it as a metadata/coverage tool, easily separable from siblings like compare_city_costs or search_lodging.

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?

It gives an explicit sequencing directive, "Call this before any broad comparison," which tells the agent when to use it. It does not name the specific sibling (compare_city_costs, compare_lodging_months) or spell out when NOT to use it, keeping it just below a 5.

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