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

Annotations already declare readOnlyHint and openWorldHint=false, so the safety profile is covered. The description adds real context beyond that: exactly what property is proven (append-only, no edit/removal/reorder), the standard it conforms to (RFC 9162), and the absence of cost ('Free'). It stops short of describing the returned proof format or verification 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?

Two tight clauses with the core guarantee front-loaded and no redundant restatement of the name. The trailing 'Free.' is terse but earns its place by surfacing a cost signal an agent would otherwise have to discover.

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 read-only proof endpoint with two params at full schema coverage and no output schema, the description covers what is proven and the cost. The remaining gap is the shape of the returned proof, which an agent may still want, but nothing critical to invoking it correctly is missing.

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 description coverage is 100%, with 'first' documented as the older signed tree size and 'second' as the newer size, omitting for latest. The description's 'two signed tree heads' corroborates this but adds no syntax, ordering, or edge-case detail beyond the schema, so the baseline 3 applies.

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 states a specific cryptographic artifact and its semantics: a proof that the log only grew between two signed tree heads, with the concrete guarantees (nothing edited, removed, or reordered) and the RFC 9162 reference. It implicitly distinguishes this from the sibling ledger_inclusion_proof by describing append-only consistency rather than membership, but it never names that alternative.

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?

There is no explicit when-to-use, no prerequisites (e.g., that you need two recorded tree heads), and no routing to alternatives such as ledger_tree_head to obtain the heads or ledger_inclusion_proof for membership. Only the 'Free' hint signals anything about cost.

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