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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real behavioral value on top: it explains that the call can block when 'wait' is set, and reassures that it never starts, renews or bills. It does not say what happens if the wait never reaches the target state (timeout/error behavior), which is the one notable gap.

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 compact sentences, front-loaded with the core read action, then the wait behavior, then the negative scope clause. No filler and every clause carries information.

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 no output schema, the description does the right thing by enumerating the returned fields (status, session, park time). Annotations carry the safety semantics. The only omission is the timeout/failure behavior of a 'wait' call that never reaches ready or parked.

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 the enum parameter is already documented ('ready' or 'parked': wait until the phone gets there). The description's 'With wait, wait until it is ready or parked' restates the schema rather than adding format or edge-case meaning, so the baseline 3 applies.

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 with scope: 'Read one phone' plus what it returns (status, session, park time). This distinguishes it from list_phones and the mutating siblings (start_phone, park_phone) without needing to open any 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 a concrete use condition: 'the way to wait for a phone that is still creating or starting', and an implicit exclusion ('It never starts, renews or bills anything'). It stops short of naming the alternative tools (start_phone/act) explicitly, so a 4 rather than a 5.

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