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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds context that this endpoint is legacy and not part of the primary buy path, but it doesn't explain what happens on invocation, what 'burn compatibility' involves, or any authentication/policy details beyond the cryptic doctrine.

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 short and front-loaded with the legacy/off-table status and the preferred alternative path. However, fragments like 'burn compatibility' and 'no_money_no_service' are jargon-heavy and may not be meaningful to every agent, slightly reducing clarity despite the compactness.

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?

The tool has only one parameter, a rich output schema, and strong annotations, so the formal metadata carries much of the burden. Still, the description never defines the tool's actual function, leaving the purpose ambiguous; an agent cannot confidently select or invoke a tool when the description only explains what it is not and when to avoid it.

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?

There is only one parameter and schema description coverage is 100%, so the schema already documents agent_id as 'Agent or wallet id that will own the session.' The description adds no further meaning about the parameter, leaving the baseline 3 appropriate.

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 never states what the tool actually does; 'Session Cert' is only labeled as legacy/non-wealth and 'kept for burn compatibility only.' This restates the title and gives a negative scope without defining the core action or resource, so an agent cannot tell what invoking it accomplishes.

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 explicitly steers agents away: 'Prefer sqlguard_challenge → Exact Pilot unlock $100 or Gateway invoice $299+.' It also states the only remaining use case ('burn compatibility only') and the policy 'no_money_no_service,' leaving little doubt about when to use this tool versus alternatives.

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