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

With no annotations, the description carries the whole behavioral burden. It usefully discloses the default-date fallback and the full set of aggregate metrics returned, but says nothing about permissions, rate limits, or whether profile changes the aggregation basis. That is real disclosure, but thin for an unannotated 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?

A single dense sentence that front-loads the scope (one day, plus profile) before the metric list. Nothing is wasted, though the middle clause mixing the profile mention with the return-field list is slightly hard to parse.

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?

No output schema exists, and the description compensates by enumerating the aggregate fields returned. The remaining gap is the unexplained `profile` parameter, which is significant given there are no annotations to fill in behavior.

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 description coverage is 0%, so the description must compensate. It does so well for `date` (ISO format, defaults to most recent) but leaves `profile` essentially unexplained — only the word 'profile' appears, with no indication of valid values or default 'median' or how it alters results.

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 a specific resource (market aggregates) and scopes it precisely to one day plus a profile, then enumerates the exact metrics returned (offers per contract type, median yearly cost, spread, cashback count, adds/withdrawals). It does not distinguish itself from siblings such as cheapest_today, which also reports same-day market figures, so it stops short of a 5.

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 implies when the tool applies (defaults to the most recent day, ISO date override) but gives no explicit when-to-use or when-not-to-use guidance against cheapest_today or cheapest_history. The default-date behavior is the only routing signal an agent gets.

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