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

With no annotations, the description carries the full behavioral burden. It does disclose a real invariant (later heads must be consistent with the saved one) and the returned fields, but says nothing about permissions, whether the log must exist, failure modes, or that this is a non-mutating read (only implied by the 'get' verb).

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 with zero filler. The resource and its payload are front-loaded, and the preservation instruction follows immediately.

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?

There is no output schema, so the description compensates by listing the returned fields (tree size, Merkle root, signature) and the consistency contract. For a zero-parameter read tool with no annotations this is close to sufficient, though a note on prerequisites or error behavior would round it out.

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 takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-parameter tool applies. The description correctly adds no irrelevant argument discussion.

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 names a specific resource ('the current signed head of the evidence log') and enumerates what it contains (tree size, Merkle root, signature), so an agent knows exactly what it retrieves. It does not, however, differentiate itself from siblings like get_checkpoint or get_ledger_attestation, which sound semantically adjacent.

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?

'Save it: any later head must be consistent with it' implies the workflow (persist this head to verify future consistency), which is useful context. But it never states when to prefer this over get_checkpoint, get_consistency_proof, or get_inclusion_proof, so the routing decision is left to inference.

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