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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower; the description still adds value by disclosing that the answer is a 'published' (precomputed) result and by enumerating returned fields in the absence of an output schema. It does not say what happens when no published pair exists (error vs. fallback), which is the main remaining gap.

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?

Three short sentences with zero waste: purpose and payload first, then the trigger, then the guardrail. All content is front-loaded and nothing is repeated from the name or title.

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 tool, the description covers purpose, trigger, payload, and a key anti-pattern, and annotations cover safety. The only missing piece is failure/empty-result behavior for pairs without a published answer, which is not addressed anywhere.

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%: both areaA and areaB already document slug/name format, length bounds, and examples. The description adds no syntax or constraint detail beyond the schema, so the 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 (Return), a specific resource (the published FairWhere meet-between answer), and scope (between two London neighbourhoods), then enumerates the payload (winner venue, minutes, gap, top venues, citation URL). An agent can distinguish this from list_meet_pairs without opening either 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?

Gives an explicit trigger phrasing ('where should we meet between X and Y') plus a negative guardrail ('Do not invent a geographic midpoint'), which is clear context for invocation. It does not name the sibling tools (list_meet_pairs, fair_shortlist) as alternatives, so routing is not fully resolved.

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