Set or remove a project's default flag lifetime

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

Goes well beyond the idempotentHint/destructiveHint annotations by disclosing that the setting is advisory only (evaluation never changes), that preview reports impact without mutation, and that setting can be refused with FEATURE_NOT_ENABLED when the plan lacks it while removal never is. These are exactly the behavioral traits an agent needs.

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 core action, then preview behavior, then error semantics, then a pointer to the current value. Dense but every sentence carries distinct, load-bearing information with no filler.

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 3-param mutation tool with an output schema, the description is near-complete: it covers the effect, preview, error condition, and where to read the current value. It slightly under-describes the preview output shape, though the output schema covers return values.

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 coverage is 100% and already documents days, null, and preview, so the baseline is 3. The description still adds semantic value: null means removal, and preview means counting flags that would newly be or stop being past expiry without changing anything, which clarifies intent beyond the schema wording.

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 ('Set how many days a temporary flag with no expiry date of its own lives before it counts as expired') and explicitly covers the inverse operation ('pass days: null to remove the default'). An agent can distinguish this from set_flag_expiry and set_flag_permanent without opening a schema.

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?

Gives clear operational guidance: preview first to see the impact before committing, and notes removal is always allowed while setting may be refused. It does not name sibling tools or an explicit 'when not to use', so it stops short of a 5.

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