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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, but the description adds a genuinely non-obvious trait absent from structured fields: Google replaces whole blocks rather than merging them, so a stale read risks clobbering untouched fields. That is exactly the kind of mutation-interaction context an agent needs before a follow-up write.

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, both load-bearing: the first front-loads the scope enumeration, the second delivers the critical pre-write warning. No filler, no restatement of the 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 read-only tool with full parameter coverage and no output schema, the description covers contents, defaults context and the read-before-write rationale. It stops short of describing response size or pagination behavior, which is the only remaining gap.

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 the baseline is 3. The description goes further by giving semantic meaning to the enum values (e.g. 'details' = description, website, phone) that the bare schema enum names do not convey, though it adds nothing about accountId or locationId behavior.

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 (read) and resource (Google Business listing) and enumerates exactly which blocks it covers — locations, details, attributes, services, placeActions, foodMenus — which maps cleanly onto the tool's scope. An agent can distinguish this from the write-side sibling (update_gbp_listing) 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?

"Read it before changing anything" gives clear workflow context for when to call it, and the replace-not-merge note explains why. It never names the alternative tool (update_gbp_listing / manage_gbp_offerings) or states an explicit when-not, so routing is implied rather than spelled out.

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