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

Goes well beyond the annotations: it reveals that the code-only form changes nothing, that the name+confirmation form creates a draft copy with rules and programs, that the originating coach keeps 10% of earnings, and that a connected account is required. These are material behavioral facts an agent could not infer from readOnlyHint/destructiveHint alone.

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?

Front-loaded with the 'Use this when...' trigger, then the two modes and the account/confirmation caveats. It is a dense paragraph rather than bulleted, but every sentence carries actionable information with no filler.

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 full schema coverage, an output schema, and non-destructive annotations already present, the description fills exactly the remaining gaps: when to use it, what each mode does, the royalty side effect, and the confirmation gating. Nothing needed to call it correctly 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 baseline is 3, but the description adds real meaning: it explains the code-only vs code+name+confirmation branching and the ordering constraint that confirmation should be true only after the coach has agreed and chosen a name. This clarifies how parameters combine, not just what they are.

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 ('copy' a 'coaching brain from a code') and distinguishes itself from siblings like find_coaching_brain and start_my_coaching_brain by describing the copy-from-another-coach scenario. The example phrase ('start my brain from K7Q2-XR4D') anchors the intent unambiguously.

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?

Gives a clear triggering condition ('when a coach has another coach's Phorme code and wants to start their own coaching brain from it') and explains the two invocation modes (code alone for preview, name+confirmation for copy). It does not name specific alternative siblings, so it stops short of full when-not guidance.

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