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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior beyond the structured fields: the default status filter (open only) and the commercial model (free within the daily allowance, then $0.001 USDC per call via x402). Rate-limit or pagination behavior is not addressed, so it stops short of a 5.

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?

Two compact sentences, front-loaded with the search axes and default scope, and the pricing clause is deferred to the end where it belongs. No padding or repeated schema content.

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?

Output schema exists, so return shape need not be described. Filters, defaults and cost model are covered, which is what an agent needs before calling. Nothing is stated about result ordering or what happens when zero filters are supplied (a plausible call, since no parameters are required).

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 100%, so all six parameters are already documented, including defaults ('open (default)', 'default 20, max 100') and the phase enum list. The description restates the main filter axes without adding format or syntax beyond the schema, which is the baseline-3 case.

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?

Specific verb 'Find' plus resource 'schools' and an explicit enumeration of the filter axes (name, postcode/district, local authority name or code, phase) and the default status scope. It implicitly separates itself from schools__near (attribute search vs proximity), but it never names the sibling tools, so differentiation is inferred rather than stated.

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 establishes a usable context: attribute-based search with 'open schools by default'. It does not say when to prefer this over schools__near or schools__school, nor does it state any exclusions or prerequisites, so usage is implied rather than guided.

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