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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true). The description adds genuine value beyond them by clarifying that no transaction is created and that the call consumes a single caller session slot — a non-obvious side effect and resource constraint. It omits auth requirements and idempotency-key behavior, so not a 5.

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, zero filler, with the core action front-loaded before the constraint caveat. Nothing is wasted.

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 five-required-parameter, write-adjacent tool with 0% schema coverage and no output schema, the description leaves the inputs undocumented (access_token, idempotency_key, wallet roles). It explains the effect and slot limit but not enough for an agent to populate the call correctly.

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 0% across five required parameters. The description weakly implies quote_id and wallet parameters ('fresh quote', 'wallet-bound') but says nothing about access_token, idempotency_key, or the source/destination distinction, so it largely fails to compensate for the coverage gap.

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 ('lock a fresh quote into a wallet-bound execution session') that clearly distinguishes it from read_session. However, it never names a sibling or explicitly contrasts with the read/prepare/observe family, so the agent must infer the boundary.

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 phrase 'reserves the caller's one active session slot' implies this precedes execution, giving implied usage context. But there is no explicit when-to-use/when-not guidance and no reference to when read_session or the prepare_* tools should be chosen instead.

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