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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description earns credit by disclosing the exact JSON shape returned and explaining that sessionEntries is the raw Claude Agent SDK transcript of tool calls/results/messages. It does not mention size limits or pagination for potentially large transcripts, keeping it at 4.

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 sentences, front-loaded with the action, then the return shape, then usage. The field enumeration is somewhat dense but earns its place given there is no output schema; little is wasted.

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 must carry the return-value burden and does so thoroughly, naming every JSON field and clarifying the meaning of the non-obvious 'sessionEntries'. Combined with the 100%-covered single parameter, an agent has everything needed to call 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?

Schema coverage is 100% and the single parameter is fully described there as 'The UUID of the investigation to fetch.' The description adds only the 'authorized to read' access constraint and no additional syntax or format detail, so baseline 3 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?

The description states a specific verb ('Fetch') and resource (the full transcript/'brief' of a Fixter investigation), and clarifies the scope ('this user is authorized to read'). It is plainly distinguishable from list_investigations, though it never names a sibling explicitly, so it stops short of the top mark.

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 gives a clear when-to-use scenario: 'Use to recall context about an investigation that the engineer is currently working on via the Fixter plugin.' That routes the agent well, but there are no explicit exclusions or named alternatives (e.g., when to prefer list_investigations or get_issue instead).

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