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

Annotations already declare this a read-only, idempotent, non-destructive computation, so the safety profile is covered. The description adds that output is both annual and monthly figures (useful since there is no output schema), but says nothing about how the override interacts with posture beyond what the schema states.

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 tight sentences with the core purpose front-loaded. The trailing promotional URL does not help an agent invoke the tool correctly, a minor dilution of otherwise efficient structure.

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 three-parameter calculator with no output schema, the description conveys the output shape (annual and monthly budget) and the two input paths, with annotations covering safety. Adequate to call correctly, though sibling disambiguation is absent.

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 100%, so the enum values, their benchmark percentages, and the customPct override are already fully documented in the schema. The description merely restates the posture list without adding syntax or precedence detail beyond the schema baseline.

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 and resource ('Size an annual and monthly marketing budget') plus the method (percentage of revenue via posture or custom override). Clear on its own, but it never distinguishes itself from siblings like brand_vs_performance_budget_allocator or cross_channel_ad_spend_allocator, which an agent must choose between.

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?

Implies two usage modes — pick a posture benchmark or supply a customPct override — which is useful context. However, it gives no explicit when-to-use/when-not guidance and names no alternative tool for adjacent budgeting tasks among the many sibling allocators.

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