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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world lookup, so the safety profile is covered. The description adds genuine behavioral value by disclosing result ordering ('best first') and the enrichment payload attached to each hit (Form A1/A2, Form 145/146, income-tax nature, GST and reporting), which annotations cannot convey.

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?

A single front-loaded sentence that states the match, the ranking, and the per-result contents with no filler. It is dense but 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?

With no output schema, the description must carry the return-value burden, and it does list what each result contains. Minor gaps remain: it does not say how many results are returned by default or how limit interacts with the ranking.

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 67% – query and direction are documented in-schema (including the inward=P / outward=S mapping), while limit has only min/max constraints. The description's 'described in plain words' merely restates the query parameter and adds nothing about direction or the limit's effect, 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 names the resource (RBI purpose codes), the input form (a payment or receipt described in plain words) and the output shape (best-first, with bank forms and tax/GST metadata), so the tool's function is unmistakable. It does not, however, differentiate itself from the sibling get_purpose_code, which an agent could easily confuse with this lookup.

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: 'fit a payment or receipt described in plain words' suggests this is the fuzzy/natural-language lookup path. There is no explicit statement of when to prefer it over get_purpose_code, no prerequisites, and no when-not guidance.

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