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

Annotations already establish readOnlyHint=true and openWorldHint=false, but the description adds real behavioral context: sibling tools return only a snippet and this one returns every field including the detail body, which explains the cost/benefit of calling it. It stops short of describing return shape or failure behavior for a malformed or unknown id.

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?

Three short paragraphs with the core action and the snippet/full contrast front-loaded, and the sibling routing at the end. The final sentence ('Use engramic_timeline to find events; use this to read one in full') mildly restates earlier content but earns its place as a routing summary.

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 one-parameter read tool with no output schema, the description is nearly sufficient: it discloses that all fields plus the detail body are returned. Naming a field or two of the returned event, or noting behavior on an unknown id, would close the remaining gap.

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% and the single id parameter already documents its format and provenance ('the id from an engramic_search or engramic_timeline hit'). The description's 'call this tool with the event's id' largely restates the schema, so 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?

The description gives a specific verb+resource: 'Read one timeline event in FULL, including its complete detail body.' It explicitly distinguishes itself from engramic_search and engramic_timeline (snippet-only) and names its counterpart engramic_topic, so an agent can select it without consulting any 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?

It supplies an explicit selection rule: use search/timeline to find events, use this tool when a hit 'warrants the whole thing.' It also names the when-not (routine scanning of many results) and the parallel pattern for topics via engramic_topic, leaving little to inference.

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