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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, so the safety profile is covered; the description earns credit by disclosing the return payload (primary-series coverage, latest value, pagination, immutable source hashes, run id, caveats) in the absence of an output schema. It also warns of incomplete universe coverage, a behavioral caveat beyond the annotations.

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?

Four compact sentences, front-loaded with the core identification and followed by scope, returns, and usage routing. It is dense but each sentence carries distinct information; the framing as a question is slightly less direct than a declarative verb-first statement.

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 discovery tool with no output schema, the description adequately covers what it searches, what it returns, and its relationship to sibling tools. The only residual gap is that the 'not the complete universe' limitation is stated without explaining what is excluded or how to enumerate the remainder.

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%, so the schema fully documents limit, query, offset, entity_type, and response_format. The description mentions the row classes that map to the entity_type enum but adds no syntax, default, or filter-behavior detail beyond what the schema already provides, so the baseline of 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 verb/resource: it searches publisher-listed holder names and stable ids in the Treasury International Capital Major Foreign Holders archive. It further enumerates the row classes it covers (holders, historical aggregates, totals, residuals, foreign-official memorandum rows), which pins down scope precisely and separates it from the history/comparison siblings.

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?

It gives clear context: 'Use this before history or comparison when a label is uncertain,' which directs the agent to call this discovery tool ahead of the history/comparison siblings. It also flags a scope limit ('this is not the complete TIC country universe') but does not name the specific alternative tools, so it stops short of the fully explicit when/when-not/alternatives pattern.

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