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

Annotations already cover readOnly/openWorld/idempotent, so the bar is lower, and the description adds real value: it discloses the shape of the returned statistics, the cohort-comparison behavior triggered by slug (percentile and deviation from median), and implies a sampling cap. It does not explain behavior on an empty or tiny cohort, which would be useful for a statistics tool.

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 tight sentences with no filler: the output shape is front-loaded, the optional comparison mode follows, and the intended question is last. Every sentence carries information an agent needs.

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 still enumerates the return contents, and all 12 parameters are documented in the schema itself. Minor gaps remain around cohort edge cases (empty results, how maxSample affects reliability) and how this differs from the market-stats sibling.

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%, so the baseline is 3, but the description meaningfully extends the slug parameter by stating that it yields a percentile and deviation from the median rather than merely being 'a listing to compare'. The other eleven parameters are left entirely to the schema, but the schema is thorough.

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 ('Market price statistics for a cohort of active sale listings') and enumerates the exact statistics produced (min, max, average, median, p25/p75, counts, average by year), so an agent knows precisely what comes back. It does not, however, distinguish itself from the sibling get_camper_market_stats, whose name suggests overlapping scope.

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 a clear usage context ('Use this to answer "is this a good price?"') and describes the optional slug comparison path, which tells the agent when to supply slug versus when to omit it. It stops short of naming alternatives or stating when not to use this tool versus get_camper_market_stats.

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