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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so the safety profile is covered. The description adds material value beyond that: the result is freshness-stamped and it discloses metering behavior (developer API keys: 2 credits, no data = no charge), which is genuine operational context an agent cannot get from structured fields.

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?

Front-loads the identity of the resource in the first clause, then tacks on freshness and cost as short trailing sentences. The middle field enumeration makes the first sentence dense, but every element carries information and nothing 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 no output schema, the description correctly takes on return-value explanation, listing the per-competitor fields plus the brand's own profile, and adds freshness and billing semantics. For a single-parameter read-only tool this is close to complete; only the missing sibling routing and domain-format hints keep it short of 5.

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?

There is one parameter and schema coverage is 100%, with the schema already documenting 'domain' including an example. The description only echoes 'for a domain' and adds no format or edge-case detail, 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?

States a specific verb (find) and resource (closest competitor brands) and enumerates the exact fields returned (name, website, country, home-market flag, match tier, own DNA profile). The 'DNA competitor set' framing distinguishes it from generic competitor feeds, though it never names a sibling to contrast against.

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?

No when-to-use, when-not-to-use, or alternative routing is given. With siblings like get_competitor_moves_feed, get_predicted_competitor_moves, and get_brand_swot_analysis all touching competitors, an agent gets no help deciding among them. Use context is only barely implied by 'last-known'.

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