John's Essentials

generate_certificate

Certificate Generator — Generate a printable certificate of achievement or completion as PDF or PNG. [category: generate]

Input Schema

TableJSON Schema

Name	Required	Description	Default
`date`	No	Free text centred at the bottom, printed verbatim ('12 June 2026' works); empty = omitted.
`format`	No	'pdf' (default) or 'png' (300 DPI Ghostscript raster). Any other value silently returns the PDF.	pdf
`template`	No	Kept for older calls; it does not change the certificate. Set the heading with Cert title and the look with Border style.	achievement
`certTitle`	No	Certificate heading. Field name is 'certTitle' — not 'title'.	Certificate of Achievement
`issuerName`	No	Printed above the signature line. Empty hides the WHOLE issuer block, issuerTitle included.
`borderStyle`	No	Unknown values fall back to gold. This is the main visual lever — it colours border, corners, and title.	gold
`description`	No	Optional body text under the title.
`issuerTitle`	No	Italic line under the signature — rendered only when issuerName is also set.
`orientation`	No	'landscape' (default) or 'portrait' (A4). Any value other than 'portrait' renders landscape.	landscape
`recipientName`	Yes	Recipient's name (REQUIRED). Field name is 'recipientName' — not 'recipient'.

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedSep 26, 2026

addedInput schema / properties / description / x-ui

Added value: +{
+  "unset_label": "Left off the certificate"
+}

addedInput schema / properties / issuerName / x-ui

Added value: +{
+  "unset_label": "Left off the certificate"
+}

addedInput schema / properties / issuerTitle / x-ui

Added value: +{
+  "unset_label": "Left off the certificate"
+}

Changed2 schema fields changedSep 11, 2026

changedInput schema / properties / template / description

Previous value: -"Accepted but does NOT change the layout — every template renders identically today; use borderStyle for the look."New value: +"Kept for older calls; it does not change the certificate. Set the heading with Cert title and the look with Border style."

addedInput schema / properties / template / x-show-when

Added value: +{
+  "borderStyle": [
+    "__never"
+  ]
+}

First observedSep 5, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations carry little signal since all hints are false/defaults, so the description bears the disclosure burden. It accurately conveys a non-destructive creation behavior that produces a printable PDF or PNG, which is consistent with annotations. It does not discuss return behavior or edge cases, though the schema's property descriptions document silent fallbacks (e.g., unknown format values returning PDF).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The core is a single short sentence that front-loads the purpose and output formats. Minor deductions for redundancy: 'Certificate Generator' repeats the annotated title, and '[category: generate]' is meta-noise that adds no value for an agent.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Invocation is well supported because the 100%-covered schema documents every parameter and its quirks, and the description pins down the purpose. However, with no output schema and uninformative annotations, the description gives no expectation of what a successful call returns (file path, download, base64), which is a notable gap for a tool with 10 parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3 even though the description itself adds no parameter detail. All 10 parameters are richly documented in the schema itself, including naming cautions ('certTitle' not 'title'), fallback behaviors, and conditional rendering, so nothing important is left undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb and resource ('Generate a printable certificate of achievement or completion as PDF or PNG'), naming both the artifact and its output formats. This cleanly distinguishes it from the many sibling generate_* tools such as generate_barcode, generate_qr_code, and generate_business_card, which target entirely different artifacts.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The 'certificate' resource strongly implies the use case — creating achievement/completion certificates — and the sibling generate_* tools are differentiated by artifact type. However, there is no explicit when-to-use statement, no mention of alternatives, and no exclusions; usage must be inferred rather than stated.

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

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