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 profile is covered. The description adds genuinely new behavioral context the annotations cannot express — the cost model (free within the daily allowance, then $0.003 USDC per call via x402) — which materially affects an agent's call strategy.

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 what is returned and followed by the cost condition. No redundant restatement of the title or schema, and every clause carries information.

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 return values need not be described, and the description plus annotations cover purpose and cost. The one material gap is the common edge case for parent lookups — what is returned when the entity has no ultimate parent — but for a one-parameter read tool the definition is otherwise complete.

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?

With a single parameter at 100% schema coverage, the schema already documents 'lei'. The description adds no format guidance (e.g., 20-character LEI syntax, whether the entity must exist in the register), so it neither compensates nor detracts — 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?

States a specific resource returned — the ultimate accounting parent of an entity — and the adjective 'ultimate' implicitly separates it from the sibling gleif__direct-parent. It is not a verb-led description, but for a read-only lookup the returned relationship is the essential information, so the purpose is clear without naming the sibling explicitly.

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?

Usage is only implied: an agent must infer that this differs from gleif__direct-parent by the immediacy of the parent (ultimate vs. immediate). No explicit when-to-use, when-not-to-use, or prerequisite (e.g., a valid LEI must already be known) is stated.

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