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

Annotations already declare readOnlyHint/idempotent/destructive=false; the description reinforces this ('Reads only') and adds genuinely new behavioral facts: the 'Not stated means that operator did not say' data-gap convention, that unstated rows are omitted, and that each column carries its own book_link. Lacks anything on cost/latency but is otherwise rich.

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-loaded with the core action, followed by a dense but purposeful return-field list and then usage routing. The long field enumeration earns its place because there is no output schema, though it reads as a run-on sentence.

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 return values and does so thoroughly (all column fields plus best flags). Usage and alternatives are complete; only minor gaps like pagination/edge behavior for a single-column result remain.

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. The description does add the '2 to 4 tours' bound and 'product_codes from search_tours' origin, but the date parameter's role (checking whether each tour runs that day) is only implied via the runs_on_date flag rather than stated as parameter meaning.

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 action (put 2-4 tours side by side) and enumerates exactly what each column returns. It explicitly distinguishes itself from get_tour_details (one tour) and search_tours (find product_codes), so an agent can route without opening a schema.

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?

'Use when the traveller asks to compare tours or which suits them' gives a concrete trigger, and the two sibling alternatives are named with their distinct purpose. When-to-use and when-to-use-something-else are both covered.

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