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

Annotations already convey readOnlyHint=false and destructiveHint=false. The description consistently implies a write operation but adds no behavioral detail beyond purpose — it doesn't mention overwriting behavior, permissions, or side effects. It doesn't contradict the annotations, but also doesn't significantly enrich behavioral understanding beyond what structured data provides.

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 short sentences with no filler. The action is front-loaded, and the use-case sentence earns its place by guiding selection. Every word is purposeful.

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 simple setter with full schema coverage and no output schema, the description plus annotations cover the essential information. It could briefly mention that setting overwrites the existing value, but that is strongly implied by 'set' and the idempotentHint. Minor gap, but overall complete enough.

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 each parameter is already documented. The description mentions 'initiative value' but adds no parameter-level detail (e.g., range, format) or relationships between parameters. Baseline 3 applies because the schema carries the full burden.

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?

Description clearly states 'Manually set initiative value' and differentiates from the rolling siblings by naming specific scenarios ('readied actions, special circumstances, or fixing rolls'). The verb-resource pair is specific and the tool's role among combat tools is unambiguous.

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 gives explicit context for when to use the tool ('Use for readied actions, special circumstances, or fixing rolls'), which implies the alternative is rolling initiative. However, it does not explicitly name the alternative tools (e.g., combat-roll-initiative) or provide 'when not to use' exclusions.

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