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

Annotations already establish readOnly/openWorld=false safety, but the description adds genuine behavioral context: the open flag comes from published schedules rather than live alerts, and results carry site counts and reservation links. That is useful beyond the structured fields, though no pagination or ordering behavior is disclosed.

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, zero waste: what is returned is front-loaded and the routing caveat follows immediately. Nothing to trim.

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 usefully enumerates the return payload (open-today, site counts, reservation links) and the schedule-vs-alert caveat. The gap is parameter coverage — limit and max_km defaults/ranges are never surfaced.

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 0% across 5 params, so the description must compensate. It implies the latitude/longitude point ("nearest a point") and the open_today_only flag ("open today by its published schedule"), but says nothing about limit or max_km, leaving two params — including the distance radius — undocumented.

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+resource+scope: NPS campgrounds nearest a point, with the fields returned (open-today status, site counts, reservation links). It differentiates from nationalparks_get_park_status by contrast, but it does not distinguish itself from the near-identical sibling campgrounds_find_near, which is a real ambiguity for selection.

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?

Explicitly scopes the tool ("Schedules only") and routes the agent elsewhere for a different need (nationalparks_get_park_status for current alerts). Clear context with one exclusion, though it never addresses the campgrounds_find_near / campgrounds_search overlap.

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