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

Annotations already declare readOnlyHint=true and idempotentHint=true, lowering the bar. The description adds useful behavior: diagrams render in Copilot Chat, Cursor, Claude, and markdown viewers, and it discloses that 'flow' is disabled because 'static call trees are misleading in D365 due to CoC and event handlers'. This context goes beyond the schema and 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 longer than average but tightly structured with labeled sections (WHEN, triggers, types, note). Every sentence earns its place, and the flow-disabled note prevents wasted calls. The trigger enumeration is somewhat verbose but directly serves the agent-routing purpose.

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 two-required-param diagram tool with readOnly/idempotent annotations, this is complete: it covers when to use, what it produces, where output renders, valid input values, the alternative sibling, and a disabled value. The absence of an output schema is compensated by explicitly stating the Mermaid output format.

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 adds meaning by expanding diagramType semantics — 'er' as 'entity-relationship diagram for a table and its relations' and 'security' as the Role->Duty->Privilege->EntryPoints chain — and by revealing that methodName is unused. This exceeds what the schema alone communicates.

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 and resource: 'Generate visual Mermaid diagrams from D365 F&O knowledge base data' for 'table relationships or security chains'. It explicitly distinguishes itself from the sibling `trace_security_chain`, so an agent can reliably separate it from nearby tools like `generate_security_report` or `get_relation_graph`.

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 'WHEN:' clause plus explicit trigger words ('generate diagram', 'diagramme', 'ER diagram') tell the agent exactly when to fire. It gives when-not guidance too: 'for the structured text chain with tables of duties/privileges/entry-points use `trace_security_chain` instead', and flags that 'flow' is disabled — no inference required.

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