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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the description's job is content disclosure — and it delivers, itemizing the stage, eight checks with evidence, figures with dates/sources/claimants, monthly counts, monetization, headroom, startup costs and risks. It omits response size/latency, which matters for a report this broad, but adds genuine context 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?

One long sentence that front-loads the core idea, but the ten-item inventory is comma-spliced and uneven in register ("the counts Horizontal makes each month", "where there is room"), making it harder to scan than a short lead sentence plus a compact list would be.

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 carries the full burden of describing return contents and does so thoroughly across all report sections. What remains missing is operational: payload size, whether the report is always fully populated, and error behavior for an invalid slug.

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 both parameters (slug with example value, language enum with default) are fully documented in the schema. The description adds nothing about slug format, language behavior, or fallback when a slug is unknown, 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?

"Everything Startup Trends has on one market" names the resource (a market report) and the scope (full detail, not a summary), which clearly separates it from search_trends and the app/service/case getters. The enumeration of contents reinforces the verb 'retrieve full record' without ever stating it outright.

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 no when-to-use guidance, no alternatives, and no exclusions — it never says to call search_trends first to obtain the slug or that this is the expensive full-detail call. The only routing hint ("slug, from search_trends") lives in the schema, not the description.

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