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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real value by disclosing the return payload (16 crimes plus four summaries, annual counts, indexes, 80% intervals, confidence, percentiles, city/county comparisons, notes). It does not state failure behavior for out-of-coverage locations or rate limits, which keeps it below 5.

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 sentences: the first establishes what the tool returns and at what geography, the second covers the calling constraint and the response contents. Every clause carries information and nothing is repeated from 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?

With no output schema, the description carries the return-value burden and does so thoroughly, and it states the input-selection rule for a 4-parameter optional-only schema. Minor gaps remain around coverage limits and how to interpret the index scale beyond "100 = U.S. rate per resident."

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 each parameter is already documented, and the baseline of 3 applies. The description does add one thing the schema cannot express — the mutual-exclusivity rule that exactly one locator must be supplied despite all four being optional — but adds no format detail for address or lat/lon 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?

The description gives a specific resource and scope: "Crime indexes for the 2020 census block group at a U.S. location." That is far more precise than the title alone and tells the agent what geography the result describes. It does not name or differentiate itself from the sibling crime_index_batch, so it stops short of a 5.

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?

"Pass exactly one of: address, lat and lon, or bg_geoid (12 digits)" is explicit calling guidance that rules out the invalid combinations an agent would otherwise try. What is missing is when to prefer this tool over crime_index_batch or how to use crime_definitions to interpret the returned crimes.

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