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

Annotations already declare readOnly, idempotent and openWorld, so safety is covered; the description adds the data source (Historic England NHLE), the name-match-only retrieval constraint, the coverage boundary, and a cost of 1 credit. That is useful context beyond the annotations, though it says nothing about result ordering or truncation behavior.

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-loads the search action and returned fields in the first clause, then layers audience, caveats and provenance compactly. The trailing parenthetical credit note and source attribution are slightly scattered but each sentence carries information.

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?

For a two-parameter read-only lookup with no output schema, the description supplies the returned field list, the source, and the key scope limitation. Minor gaps remain around result ordering and what happens on zero matches, but an agent has enough to call it correctly.

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 already documents the name substring with case-insensitivity, length bounds and an example, plus the limit range and default. The description only restates 'by name', adding no matching semantics beyond the schema, so baseline 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?

States a specific verb (Search) and a precisely named resource (England's Register of Parks and Gardens of Special Historic Interest), plus the fields returned (grade, date registered, area, official link). The named register distinguishes it from the other heritage-listing siblings such as listed_building_search and scheduled_monument_search without needing to mention them.

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?

Gives clear context ('For garden visitors, estate owners and planners') and a genuine exclusion ('Name match only; covers registered landscapes, not every public park'), which tells an agent when not to use it. It stops short of naming an alternative tool for public parks or for spatial queries.

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