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

Beyond the readOnlyHint annotation, the description discloses the return content (full block payloads and media summaries) and the editorial workflow implication. It adds useful behavioral context without contradicting the annotations.

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 sentences, front-loaded with the purpose and return contents, followed by a directly actionable caveat. Every clause contributes information and there is 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?

For a read-only tool with a readOnlyHint and fully documented parameters, the description covers the key behavioral details and the read-before-edit workflow. It does not explicitly describe pagination, but limit and cursor are already documented in 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?

The input schema already documents all four parameters with full descriptions and constraints, so the description need not repeat them. The description adds no parameter-level detail beyond what the schema provides, earning the baseline score.

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 uses a specific verb ('read'), identifies the resource ('a trip's timeline'), and details what is returned ('every block with its full payload, plus a summary of the media it references'). It also distinguishes itself from update_block by explaining the replacement semantics.

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?

It explicitly tells the agent to read from this tool before editing because update_block replaces a payload whole, which is clear usage guidance. It does not mention other siblings like list_media or get_trip_state, so it is not exhaustive.

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