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 adds real context beyond them: it enumerates what is returned (including 'immutable provenance' and a canonical download URL) and draws a hard boundary ('does not fetch or inspect the geodatabase'), which prevents misuse of the tool as a data-fetch.

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 dense sentences, front-loaded with the operation and key, then return payload, then usage routing and exclusion. No filler or repetition of the schema.

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 with full schema coverage and no output schema, the description supplies the lookup semantics, the return shape, and the sibling routing an agent needs. Nothing material is missing.

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%, so the schema carries the parameters (including the regex pattern). The description still adds value by stressing 'exact DFIRM ID', signaling exact-match lookup semantics rather than fuzzy search, which complements the schema's syntactic pattern with intent.

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), a specific resource (one self-hosted FEMA NFHL inventory unit), and the exact lookup key (DFIRM ID). It also enumerates the returned fields and names the sibling it is not (flood_zone_lookup), so the agent can place it without opening a 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?

Explicitly positions usage: 'Use this to produce acquisition evidence after search' establishes the workflow slot, and 'use flood_zone_lookup for address/coordinate zone questions' names an alternative and the condition selecting it. It stops short of naming fema_nfhl_search_inventory directly, but the sequencing is clear.

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