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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the read-only safety profile is covered. The description adds useful behavioral constraints beyond annotations: it never returns values, only metadata, and it specifies that `expiresAt` is null for branches without a TTL. This gives an agent confidence about exactly what to expect.

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?

The description is tight and every sentence earns its place: purpose, scope, data boundary, use cases, and return shape all appear without padding. The key qualification ('never values') is front-loaded, and the inline JSON example communicates the return structure compactly.

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?

There is no output schema, so the description carries the burden of explaining the return contract; it does so with an explicit row shape and the null-TTL rule. It also explains why an agent would call it (before delete_branch, spotting expired branches) and how to narrow scope, making it complete for a read-only list tool.

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%, so all three parameters (app, env, org) already have descriptive schema text. The description reinforces the `env` narrowing behavior and ties the returned slug to delete_branch, but it does not add substantial new parameter-level meaning beyond what the schema already provides.

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 opens with a specific verb and resource: 'List ephemeral branch configs (per-PR / preview environments)', and scopes it to an application or branches forked from one environment. It also states the data boundary ('Names, parents, and expiry only — never values'), which makes it clear this is not a generic environment or secret listing tool.

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 usage instructions: 'Use it before delete_branch to find a branch slug, or to spot branches that have already expired.' It also explains the narrowing behavior of the optional `env` parameter versus omitting it, providing enough context for an agent to decide when to call this tool.

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