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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the authorization requirement ('needs project Read'), the 4,000-character truncation applied to source text, and the fact that the payload mirrors the Trace sheet. Missing only pagination/error behavior.

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?

Front-loaded with the core scope, then the returned fields, then the truncation caveat and auth requirement — no filler sentences. The field enumeration is dense and slightly run-on, but every clause carries information an agent needs.

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 carries the full burden of describing returns and does so thoroughly, including truncation of source text; it also flags the read-permission requirement. It stops short of covering not-found/cross-project id behavior, but it is otherwise sufficient for a two-parameter read 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%, and both 'id' and 'project' are fully documented in the schema itself (including the single-live-project default). The description adds only the framing 'by its id', so the baseline 3 for schema-driven parameters is correct.

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 precise resource and scope ('One memory or source by its id') and then enumerates exactly what the node contains — headline, kind, data point, revision, timestamps, validity, currency, and input/output counts. That field inventory plainly separates it from lineage- or roots-oriented siblings like get_lineage and find_trace_roots without opening a 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?

Usage is only implied: the id is described in the schema as coming from find_trace_roots, get_lineage or explain_ingestion, and the description adds the 'needs project Read' prerequisite. It never states when to pick this over those sibling retrieval tools or when the call would fail. Adequate but with a clear gap.

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