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

Annotations declare readOnlyHint=true and destructiveHint=false; the description adds substantial context: it serves as a liveness probe, costs 0 IU, returns a dictionary with specific fields, and non-2xx responses raise a clean MCP error. This goes far beyond the annotations and prepares the caller for observable behavior.

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 well-structured with clear sections (Purpose, Use when, Do not use when, Capability class, Path fit, Cost, Returns). It is somewhat wordy, but every section adds meaningful context for a tool with no parameters, so it earns its length.

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 zero-parameter tool with an output schema, the description is exceptionally complete: it covers the tool's role, return fields, cost, error behavior, and relationship to the broader system. There is no missing context needed for correct invocation.

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?

The tool has zero parameters, so the description doesn't need to explain parameters. The baseline for zero params is 4 per the rubric, and the description appropriately focuses on the response structure and use cases, making the parameter absence self-evident.

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?

Description states the specific verb+resource: 'Verify sealed engine identity — returns the sha256 of the running scoring binary.' It clearly distinguishes itself from sibling tools by explicitly noting it is not a scoring tool and returns identity/liveness only, not entropies.

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?

Provides explicit 'Use when' and 'Do not use when' sections, and even mentions the in-process alternative for production. This gives the agent clear guidance on when to select this tool versus scoring tools.

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