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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description adds one genuine behavioral trait — 'adds an item and changes nothing else,' i.e. it is additive and does not mutate existing rules. It says nothing about the durable-retry/idempotency behavior the schema exposes, which is the notable gap.

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 short sentences with no filler; the resource and location are front-loaded before the behavioral note. Nothing is redundant, though the second sentence is thin enough that it borders on padding.

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 six-parameter mutation tool with annotations covering safety and no output schema, the description is minimally adequate: it names the resource, the target location, and the additive nature of the write. It omits creation-vs-update routing and any mention of the retry/idempotency parameters, leaving material gaps for an agent deciding how to call it.

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 sits at 67%, so the schema documents most parameters (body, operation_id, idempotency_key, workspace_id). The description adds meaning for the otherwise undocumented 'path' parameter by calling it 'workspace-relative,' but says nothing about the 2048/500 length limits or the default '/' location beyond that phrasing.

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 concrete verb and resource: 'Save a new rule' at a 'workspace-relative path in the connected Pathrule workspace.' The word 'new' distinguishes it from pathrule_update_rule and the read/delete/history siblings without needing their schemas. It does not, however, draw any explicit line against the parallel write_memory/write_skill siblings.

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?

The description never states when to choose this tool over pathrule_update_rule or the write_memory/write_skill alternatives. 'Save a new rule' implies creation, but there is no explicit prerequisite, no when-not-to-use note, and no routing to a sibling for the update or overwrite case.

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