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

Annotations provide safety hints (readOnlyHint, destructiveHint), and the description adds value beyond them by disclosing output boundaries: it returns per-round periods and document metadata but explicitly not Base64 document bodies. It also instructs checking official materials for rates and exceptions before estimation, adding workflow behavior not present in 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?

Three sentences front-load the core action and output scoping, with no redundant phrasing. The third sentence is dense but contains a useful verification instruction, so no sentence is wasted.

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?

With one required parameter and no output schema, the description covers what is returned and the key non-return of Base64 documents, which is enough for correct invocation. It could be more specific about the response structure, but the low complexity and pipeline guidance make the definition adequately 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?

Schema coverage is 100% and describes the subsidy_id format, so the schema does most of the work. The description contributes the key source relationship: the ID must come from search_subsidies, which is meaningful beyond the format constraints.

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 and resource: it fetches the J-Grants detail API V2 using a subsidy ID returned by search_subsidies. It also distinguishes itself by naming what it returns (application periods, document metadata) and what it does not return (Base64 document bodies), separating it from sibling tools.

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 gives clear workflow context: use it after search_subsidies, with the ID that tool produced, and before estimating amounts. It does not explicitly list exclusions or alternative tools, but the intended position in the pipeline is evident.

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