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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: the not-found-doesn't-mean-failed caveat and the credential-handling guarantee (never in URLs, never echoed in errors). These are genuine behavioral disclosures a caller 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?

Three sentences, purpose front-loaded, then the recovery caveat, then the credential note. Every sentence carries information, though the credential sentence reads as a slightly tangential addendum.

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?

No output schema and no annotations describing the response, so the description should say more about what a status/recovery call returns (e.g. whether it yields the session id or a settled/in-flight state). The not-found caveat helps but the return contract is left implicit.

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 50%: the credential parameter is documented, but idempotency_key only carries a pattern. The description compensates somewhat by explaining the credential can be supplied as an argument or via the Authorization header, but adds no meaning for the key itself. Baseline 3 fits.

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 (recover) and resource (uncertain session creation) keyed by Idempotency-Key, which clearly frames it as a status/recovery check distinct from the many create_* siblings. It doesn't name a specific alternative tool, but the intent 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?

"Recover an uncertain session creation" plus the note that "not-found does not prove an in-flight request cannot still settle" gives the agent clear conditions for when to call this and how to interpret the result. No explicit exclusions or named sibling alternatives, so not a 5.

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