Delete Filter

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

Annotations already declare destructiveHint=true and idempotentHint=false, yet the description adds real context: indices shift up after deletion (why a second call with the same index is unsafe), and that deletion may be refused or prompt the user depending on the account's block-setting. It does not describe the failure response shape, but the operational caveats are well beyond the annotation set.

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, front-loaded with the action and index source, then the mutation caveats. Dense but every clause carries information; the nested quoting in the second sentence makes it slightly harder to parse than necessary.

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 destructive tool with no output schema, this covers the key things an agent needs: which index space to use, index invalidation, and conditional refusal. Return/error format is absent but that gap is minor given the lack of an output schema.

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% and the schema already documents both accountId and filterIndex including the 'from listFilters' hint. The description adds only the shift-after-delete note, which is more behavioral than parameter-level, so 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 and resource ('Delete a mail filter') plus the addressing scheme ('by index (from listFilters)'), which distinguishes it cleanly from siblings like listFilters, updateFilter, and createFilter.

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?

Tells the agent where filterIndex comes from (listFilters) and explains the conditions under which deletion succeeds or is refused ('Always block' vs 'Ask me each time'). It stops short of naming updateFilter as the alternative when the user only wants to change a filter, so it is strong but not fully routing.

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