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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description does not need to restate safety. It adds useful behavioral context by specifying the two retrieval modes (whole registry vs. object-scoped) and the included fields (evidence tier, reliability, access date). This goes beyond the structured annotations without contradicting them.

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 two sentences with no wasted words. It front-loads the core behavior, then immediately gives usage guidance and a sibling-tool distinction. Every clause earns its place.

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?

Given the single optional param, rich annotations, and presence of an output schema, the description covers what the tool does, when to use it, how to toggle scope, and how it relates to get_entity. Nothing essential is missing for an agent to select and invoke it correctly.

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 provides 100% parameter description coverage, including the meaning of object_id and the omit-to-get-whole-registry behavior. The description mirrors this guidance rather than adding new parameter semantics. A baseline of 3 is appropriate because the schema carries the load.

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 clearly states the tool returns the instance's whole source registry or sources cited by one object, each with evidence tier, reliability, and access date. It distinguishes itself from get_entity by explicitly noting that get_entity already tells which sources a claim cites. The verb 'get' plus resource 'sources' makes the scope precise.

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 description explicitly tells when to use this tool: when needing the registry entry behind a citation or the whole registry to judge the corpus. It also provides an alternative, get_entity, and implies when not to use get_sources, since get_entity already provides which sources a claim cites. This is strong practical routing guidance.

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