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

Annotations already declare read-only/idempotent/non-destructive, but the description goes well beyond them: it clarifies the parser does zero execution or evaluation, states the 32 KB payload cap and 60 RPM rate limit, discloses demo/L402 payment options (75 sats), and names the HTTP 400 failure mode. This is exactly the operational context structured fields cannot carry.

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 purpose and scope, then usage/routing, then operational constraints. It is dense but every clause carries information; the only minor cost is the packed parenthetical operational block that takes a second read.

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 stateless parser with a full output schema, the description supplies everything needed: scope, supported languages, usage conditions, sibling routing, resource limits, payment mode, and error behavior. Return values are correctly left to the output schema.

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 schema already documents both parameters, making 3 the baseline. The description mentions 'source_text' and 'enum defaults', which is mildly useful but also slightly inconsistent with the schema (property is named 'code' while the required key is 'source_text'), so it adds no reliable meaning beyond 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 specific verb and resource (static AST parse / symbol extraction) and enumerates exactly what is extracted: imports, exports, classes, interfaces, functions, call edges, cyclomatic complexity, Halstead volume, across five named languages. It also distinguishes itself from the sibling audit_module_dependency_cycles, so an agent can route 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?

Gives an explicit when-to-use ('mapping internal functions, call graphs, and complexity hotspots of a source file before refactoring') and a named alternative for the adjacent case ('for analyzing cross-file import DAGs and circular dependencies, use audit_module_dependency_cycles instead'). Both the condition and the counter-condition are spelled out.

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