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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true), the description discloses the auth requirement ('Needs the user's Cotlet API key with access to this app'), the reversibility profile ('one removal undoes it'), and the side-effect scope ('reaches no one directly'), which together justify running without confirmation. This is substantial context the structured fields do not carry.

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?

The purpose is front-loaded, but the description restates itself: 'Add a gift from any store by product URL' vs 'Adds a gift to your registry from a product page', and 'Joy fills in the title and price when it can' vs 'Joy reads the title and price from the page when it can.' Roughly a third of the text is redundant.

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 7-parameter mutation tool with no output schema but full schema coverage and rich annotations, the description supplies the missing pieces an agent needs: auth scope, auto-fill behavior, reversibility, and no-notification side effects. Only minor gaps remain (e.g., nothing on currency or quantity defaults beyond the 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%, so baseline would be 3, but the description adds behavioral meaning about title and price (Joy auto-fills from the page when it can, otherwise set them yourself) that clarifies why these optional params exist. It doesn't cover note, quantity, or event_id, leaving those entirely to the schema.

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 ('Add') and resource ('a gift to your registry') plus the key input (product URL from any store), so an agent can distinguish it from joy_list_registry_gifts or joy_list_received_gifts at a glance. The core purpose is unambiguous despite some restatement.

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 ('Add a gift... by product URL'); there is no explicit when-to-use, when-not-to-use, or named alternative among the joy_* sibling tools. The 'set them yourself otherwise' and 'Mark it Our Most Wanted' lines guide parameter choices rather than run-time context.

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