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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety and determinism profile is covered. The description adds meaningful behavioral context beyond that: the signal is compact, it deliberately omits a score and refuses to allow or deny, clarifying it is advisory input rather than a decision. It does not mention rate limits or what a missing/low-confidence signal looks like.

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 short sentences, front-loaded with the action and payload contents, followed by the crucial negative scoping ('No score, no allow or deny'). Every clause earns its place with no filler.

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?

An output schema exists, so the description need not document the return shape in detail. It covers the action, the input (via schema), the advisory (non-decision) nature, and the intended consumer, which is complete enough for a single-param read-only tool.

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?

Only one parameter, endpoint, and schema description coverage is 100% (a https URL of the agent or MCP endpoint). With zero params the baseline is 4, and here the single param's semantics are already fully documented in the schema; the description adds no additional param detail, which is acceptable given full coverage.

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 clear verb and resource: returns the compact NENRIN signal for an endpoint, enumerating what the signal contains (anchored measurement counts, witness diversity, freshness). Sibling names like nenrin_ledger_entry and nenrin_witness are not explicitly contrasted, so it falls short of 5, but the purpose is unmistakable.

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 implies the consumer (a trust engine or orderer that reads a compact shape) but gives no explicit when-to-use versus sibling tools, and no when-not-to-use. Usage is only inferable from the phrase 'in a shape a trust engine or orderer can read'.

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