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

Beyond the annotations, the description explains key behaviors: summary is the only original writing, refs must point to existing blocks, and calls are merge-like after the first. This is valuable context that annotations alone do not provide, and it is consistent with readOnlyHint=false and idempotentHint=true.

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 description is compact and front-loaded, opening with purpose and then providing constraints, call pattern, and guidance. Every sentence earns its place and there is no filler or redundant restating of the title.

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?

Covers purpose, ref semantics, partial-update behavior, reading current state, and external guidance. Minor ambiguity remains about which four fields are required on the first call, and the replace behavior is only in the schema, but the overall definition is complete enough for such a complex tool.

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%, so the baseline is 3. The description adds cross-parameter meaning by clarifying that ref fields reference existing blocks, that summary is original, and that partial updates are allowed after the first call. It does not repeat each parameter's schema text, which is appropriate.

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?

Description states a specific verb and resource: sets a trip's cover and highlights, and characterizes it as the curated layer above the timeline. This clearly separates it from siblings like set_trip_ending, set_trip_theme, and update_trip without needing to open schemas.

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 explicit workflow guidance: first call needs all four fields, later calls may send only changes, and the current head should be read via get_trip_state. It also points to learn('head') for further guidance. It does not explicitly state when not to use this tool versus alternatives, but the usage context is strong.

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