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

Annotations already flag destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description earns credit for disclosing a real side effect not in the annotations — that changing the origin invalidates endpoint ownership verification — plus the normalizing behavior. It does not state auth requirements or what a no-op re-submit does.

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, no filler, with the core action and its most surprising consequence both front-loaded.

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 small, annotated, two-parameter mutation this covers the essentials but leaves gaps: no mention of what the call returns (which matters since there is no output schema and the stored origin may be normalized), no permission/auth context, and no explicit relation to agent_endpoint_verify.

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 50%: agent_key is documented in the schema while endpoint only has format/pattern constraints. The description adds real meaning for endpoint (public HTTPS, stored as a normalized origin, path presumably stripped) but says nothing further about agent_key, so it is a modest improvement rather than compensation.

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 names a specific verb ('Store') and resource (this agent's public HTTPS endpoint) and adds that the value is normalized to an origin, which tells the agent the stored value may differ from the submitted URL. It does not explicitly contrast with the sibling agent_endpoint_verify, so it stops short of 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?

Usage is only implied: this is the step that registers an endpoint, and the note that changing the origin clears ownership verification hints that agent_endpoint_verify must be re-run afterwards. There is no explicit statement of when to call this versus verify, or of prerequisites such as a registered agent key.

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