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

Goes well beyond the annotations: it discloses audience impact ('People who can see the trip see them'), the default per-call confirmation and that it can be switched off, a pre-call confirmation requirement because it 'Reaches other people', and the auth need ('Cotlet API key with access to this app'). This is exactly the extra context annotations don't 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?

Purpose is front-loaded, but there is redundancy: 'Add photos or videos' is restated as 'Attaches photos or videos by URL', and the confirm-before-call idea appears twice ('By default you confirm each call' and 'confirm with the user before each call'). Trimming would sharpen it.

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 no output schema, the description still covers the audience effect, confirmation policy, and key requirement, which is enough for a 2-parameter attach tool. It could note where URLs must be reachable from or any per-step media limits, but the essentials are present.

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 is 100%, with step_id documented as coming from list_steps and photo_urls as photo/video URLs. The description confirms URLs (not uploads) and the existing step, but adds little beyond the schema, so the 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 ('Add photos or videos') plus the scope ('to an existing step'), and specifies the attachment mechanism ('by URL'). An agent can tell this apart from a step-creation sibling like add_step without opening either schema.

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 'existing step' constraint implies a prior step_id is needed, but the description never names or contrasts an alternative sibling (e.g., add_step for creating a step). The confirmation guidance is offered, but the when-to-use-vs-alternative routing is only implied.

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