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

Annotations already carry the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the burden is lower. The description adds only that `include` embeds related records, and says nothing about not-found behavior, whether `cancelled` affects visibility, or response shape — modest added value beyond structured fields.

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 tight sentences with the cardinality constraint front-loaded and no filler text. The trailing raw endpoint is marginally useful for mapping but is the only slightly redundant element.

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?

A simple single-record read whose parameters are fully documented in the schema and whose safety profile is covered by annotations. Nothing essential is missing for correct invocation, though a note on missing/soft-deleted records would round it out.

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 baseline is 3; the schema already documents `include`, `cancelled`, and the UUID source. The description echoes the `include` concept ('the related records you ask for') without adding syntax or semantics beyond the schema.

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 ('GET ... by UUID') and resource ('lettings instruction'), plus the key differentiator that it returns a single record with an `include` expansion. It does not explicitly name street_list_lettings_instructions as the plural alternative, but 'One ... by UUID' makes the single-vs-list split obvious.

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?

Usage is implied rather than stated: an agent can infer it should use this when it has a UUID and wants the expanded record. There is no explicit 'use this instead of X when...' routing or mention of prerequisites such as where the UUID comes from (the schema covers that, not the description).

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