callgraph

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral detail: mermaid output, imports appear as leaf nodes, and a %% comment line reports nodes dropped by max_nodes — telling the agent how truncation is surfaced rather than silent. It stops short of describing overall response shape or pagination, 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?

A single dense sentence plus one exclusion clause; the primary behavior and output format are front-loaded and every clause carries information (direction, leaf handling, truncation marker, alternatives).

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 takes on the burden of describing the return value and does so (mermaid text, imports as leaves, %% truncation line). Combined with annotations covering read-only status, 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%, so the baseline is 3; the description still adds value by explaining the semantic consequence of callers=true (inverted traversal) and, importantly, that exceeding max_nodes produces a %% line counting the cut nodes rather than an error. That truncation contract is not in the schema.

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?

States a concrete verb (draw), resource (a function's call graph), and output format (mermaid), plus the direction switch via callers=true. It explicitly names the sibling tools it is not (reaches, xrefs), so an agent can distinguish it without opening 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?

Provides explicit exclusions with alternatives: 'Not for one path (use reaches) or a caller list (use xrefs).' This is the when-not/use-instead guidance pattern, requiring no inference from the agent.

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